JP4586124B2 - Non-contact inspection method and non-contact inspection device for electrical connection - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-contact inspection method and non-contact inspection that enable non-contact inspection of an electrical connection portion between a substrate on which a large number of capacitive circuit elements are arranged and arranged, such as a liquid crystal substrate and an organic EL substrate, and leads of electronic components. Relates to the device.
[0002]
[Prior art]
The liquid crystal display device includes a first glass substrate on which a transparent conductive film is formed, a large number of thin film transistors arranged in a matrix at predetermined intervals, a pixel electrode connected to the drain electrode, and a thin film transistor arranged in a vertical direction. A source electrode is connected in common, and a second glass substrate connected in common with thin film transistor gate electrodes arranged in a lateral direction is opposed to each other, and liquid crystal is sealed between the glass substrates to form a liquid crystal cell. Display is performed by applying a control signal to the electrode and the source electrode to control opening and closing to select a pixel electrode. The liquid crystal cell is also a circuit board having a structure in which a large number of capacitive circuit elements having liquid crystal sandwiched between transparent conductive films and pixel electrodes are arranged in a matrix.
[0003]
The number of gate electrode lines and source electrode lines connected in common is determined by the number of pixels. For example, in the case of an XGA color liquid crystal display device, the aspect ratio is 3: 4, the pixel size is 260 μm, the number of pixels is set to 768 pixels vertically and 1024 pixels horizontally, so 768 gate electrode lines and source electrode lines are provided. Requires a total of 3840 electrode lines of 1024 × 3, and the interval between these electrode lines is limited by the pixel size. On the other hand, it is difficult to connect a large number of electrode lines to the liquid crystal cell at a minute interval, and connection reliability cannot be guaranteed.
[0004]
Therefore, the gate driver IC and the source driver IC are connected to the peripheral edge of the circuit board following the sealing step of sealing the liquid crystal between the first and second glass substrates, and the number of electrode lines externally connected to the liquid crystal cell is reduced. I am letting. The number of input lines can be reduced by using, for example, three driver ICs with 256 output lines for the gate electrode lines and eight driver ICs with 384 output lines for the source electrode lines. Since the number is small, the interval can be widened and external connection becomes easy.
[0005]
A driver IC having a TAB structure or a flip chip structure is generally used to arrange a large number of thin leads in the same plane at a fine interval, and is used as a conductive adhesive for connecting the electrode lines on the liquid crystal cell and the leads of the driver IC. An anisotropic conductive film (ACF) or anisotropic conductive paste (ACP) that can connect a large number of electrode wires and leads together is used.
[0006]
When the driver IC is connected to the liquid crystal cell in this way, a test signal is supplied to each input line of the gate driver IC and the source driver IC, and a predetermined pattern is displayed on the liquid crystal screen, so that the quality of the display device can be determined. Become.
[0007]
In Patent Document 1, an inspection pattern is displayed on a display surface of a liquid crystal panel by a liquid crystal display pattern driving device, is imaged by a recognition camera, analyzed by a recognition data processing unit, and optimally adjusted by backlight illumination. An automatic liquid crystal panel inspection apparatus that eliminates individual differences is disclosed. The same document also discloses that the electrical connection between the liquid crystal cell and the driver IC is judged by blowing hot air on the anisolum (anisotropic conductive film) or applying vibration to the TAB (driver IC). Yes.
[0008]
Patent Document 2 discloses a method for inspecting a conductor circuit board comprising a stimulator that radiates electromagnetic waves to the conductor circuit board, a non-contact sensor for signal detection, and a ground plane shield that insulates the stimulator from the sensor. Is disclosed. This is because the sensor detects the displacement current that occurs in the conductive pattern of the conductor circuit board that has received electromagnetic waves, and the detected displacement current is analyzed by a computer, thereby short-circuiting or opening the conductive pattern on the conductor circuit board. It is disclosed that a defect can be detected, and that it can be applied to a printed circuit board, a liquid crystal display board, or the like as a conductor circuit board.
[0009]
[Patent Document 1]
JP-A-7-199138 (paragraph numbers 0014 to 0018, FIGS. 1 to 2)
[Patent Document 2]
JP-A-8-278342 (paragraph numbers 0015 to 0027, FIG. 1).
[0010]
[Problems to be solved by the invention]
By the way, the liquid crystal cell and the driver IC need to be connected not only to each electrode line and output line but also to a power supply line, a ground line, etc. In the case of an XGA color liquid crystal cell, there are 3840 or more electrical connections. If the connection is poor even at one of the electrical connection portions, a line defect or noise appears on the display screen, resulting in a defective liquid crystal display device.
[0011]
For this reason, when such a connection failure is found, the anisotropic conductive film is peeled and removed using a solvent, a new anisotropic conductive film is attached again, and the driver IC is reconnected to improve the quality.
[0012]
However, in the inspection method disclosed in Patent Document 1, after the circuit board and the output line of the driver IC are electrically connected using an anisotropic conductive film or the like, the TAB package is further folded to input the driver IC. An inspection signal cannot be supplied to the input line of the driver IC unless the line is fixed to the outer periphery of the liquid crystal cell.
[0013]
In addition, since the driver IC is actually operated to display the inspection pattern on the liquid crystal screen and judge the quality, a dedicated inspection position is required, and the work man-hours from the connection of the driver IC to the inspection increase. When the defect is found, there is a problem that the cost required for the separation, replacement and re-inspection work of the driver IC is high.
[0014]
In addition, the inspection method disclosed in Patent Document 2 uses a sensor to detect a displacement current generated in a conductive pattern in a non-contact manner using electromagnetic waves, thereby enabling detection of defects such as a short circuit or an open circuit in a conductor circuit board. Therefore, applicability to liquid crystal display devices has also been suggested.
[0015]
However, since the displacement current generated by electromagnetic waves is weak and easily affected by external noise, a ground plane shield that shields the signal detected by the sensor from external noise is indispensable, so a dedicated inspection position is required. .
[0016]
In addition, the liquid crystal cell is equivalent to a circuit board in which a large number of capacitive circuit elements each having a gate-drain capacitance and a source-drain capacitance connected in series are connected in parallel to the capacitance of the liquid crystal itself. The displacement current generated by the electromagnetic wave is dispersed in a large number of capacitive circuit elements and flows into the circuit board, so that the electrical connection between the circuit board electrode line and the driver IC output line is reliably detected. There was also a problem that it was difficult to do.
[0017]
[Means for Solving the Problems]
The present invention has been proposed for the purpose of solving the above-described problems. A circuit board having a large number of capacitive circuit elements connected in parallel on an insulating substrate and arranged in parallel, and a conductive pattern connected to one end of the circuit element, A high-frequency magnetic field generating means and an inspection pickup coil are placed in proximity to an electrical connection portion in which a lead of an electronic component is electrically connected to the conductive pattern via a conductive adhesive, and a high-frequency current flowing through the pickup coil is measured. Provided is a non-contact inspection method for an electrical connection part for determining whether or not the electrical connection part is connected based on a change.
[0018]
The electrical connection portions are arranged in parallel at predetermined intervals along the periphery of the insulating substrate, and the high-frequency magnetic field generating means and the pickup coil are moved relative to each other across the electrical connection portion. In this case, the high-frequency magnetic field generation means and the pickup coil are moved relative to the electrical connection portion at a constant interval, and the high-frequency magnetic field generation means and the pickup coil are moved relative to the electrical connection portion at a constant speed. The inspection accuracy can be stabilized by making the relative movement with.
[0019]
Moreover, the high frequency magnetic field generating means and the pickup coil may be provided independently, or the pickup coil can also serve as the high frequency magnetic field generating means. Since the pickup coil is also used as the high-frequency magnetic field generating means, the size can be reduced, so that the high-frequency magnetic field can be concentrated on the electrical connection portion to be inspected and the inspection accuracy can be improved. Further, magnetic field converging means for converging the high frequency magnetic field on the electrical connection portion can be disposed between the high frequency magnetic field generation means and the electrical connection portion.
[0020]
Thereby, since the high frequency magnetic field can be concentrated on the electrical connection portion, the influence of the external noise can be alleviated and the inspection accuracy can be improved. It is also possible to arrange a magnetic circuit that circulates the high-frequency magnetic field from the high-frequency magnetic field generating means to the pickup coil through the electrical connection portion.
[0021]
The inspection method according to the present invention can be applied to a circuit board in which a large number of capacitive elements such as a liquid crystal substrate or an organic EL substrate are arranged in a matrix.
[0022]
Moreover, the test | inspection method by this invention is applicable to the conductive connection part using an anisotropic conductive film or anisotropic conductive paste as a conductive adhesive.
[0023]
In the present invention, a large number of capacitive circuit elements are connected in parallel on an insulating substrate and arranged in parallel, and the conductive pattern connected to one end of the circuit element and the lead of the electronic component are electrically connected via a conductive adhesive. A circuit board support for supporting the connected circuit board, a magnetism generating means for generating a high-frequency magnetic field and relatively moving across the electrical connection portion of the conductive pattern and the electronic component on the circuit board, and the magnetism generating means Electricity including a pickup coil that relatively moves across the electrical connection and detects a high-frequency current, and a connection quality determination unit that determines whether or not the electrical connection is connected from a change in the high-frequency current flowing in the pickup coil Provided is a non-contact inspection device for a mechanical connection.
[0024]
This apparatus is configured to move the high-frequency magnetic field generating means and the pickup coil relative to the electrical connection portion at a constant speed while maintaining a constant interval.
[0025]
Further, since the pickup coil can also be miniaturized by using it as a high-frequency magnetic field generating means, height adjustment and movement are facilitated, and magnetism can be concentrated on the part to be inspected, so that the inspection accuracy can be improved.
[0026]
In addition, magnetic field converging means made of a highly permeable material is disposed between the high-frequency magnetic field generating means and the electrical connection portion, so that the high-frequency magnetic field can be converged on the electrical connection portion, thereby improving inspection accuracy.
[0027]
Further, by arranging a magnetic circuit that circulates the high-frequency magnetic field from the high-frequency magnetic field generating means through the electrical connection portion to the pickup coil, magnetic leakage can be reduced and the electric power required for the inspection can be reduced.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. In the figure, reference numeral 10 denotes a liquid crystal cell, in which a pair of glass substrates 12 and 14 are opposed to each other via an annular seal portion 16, and liquid crystal (not shown) is sealed in a region surrounded by the annular seal portion 16. A large number of thin film transistors (not shown) are arranged on the inner surface of the glass substrate 12, and the drain electrodes thereof are connected to the pixel electrodes, and the source electrodes of the thin film transistors arranged in one direction are connected in common. The gate electrodes of the thin film transistors arranged in a direction perpendicular to the electrode are connected in common, and each electrode line is drawn out to the outer periphery of the glass substrate 12. The illustrated example shows a conductive pattern 18 having one end connected to the source electrode line and the other end drawn to the outer peripheral portion of the glass substrate 12.
[0029]
As shown in FIG. 2, the liquid crystal cell 10 includes a source electrode line indicated by a solid line and a gate electrode line indicated by a dotted line connected to a conductive pattern 18 in a capacitance formed by liquid crystal via an interelectrode capacitance of a thin film transistor. It is also a circuit board in which capacitive circuit elements connected in series are arranged in a matrix.
[0030]
Reference numeral 20 denotes a liquid crystal cell support (circuit board support) that supports the liquid crystal cell 10, and the liquid crystal cell 10 can be moved in a horizontal plane. Reference numeral 22 denotes an anisotropic conductive film disposed across the conductive pattern 18 connected to a set of source electrode lines, and reference numeral 24 denotes a driver IC having a TAB structure, which has a rectangular through window 26a. A plurality of fine conductive patterns 28 and 30 are formed on both sides of the through window 26a on the insulating film 26, and inner leads are formed by extending the inner ends of the conductive patterns 28 and 30 into the through window 26a. The outer leads 28a and 30a are formed by protruding from the insulating film 26. An IC chip 32 has a large number of protruding electrodes 32 a and 32 b, and the protruding electrodes 32 a and 32 b are thermocompression bonded to the inner end portions of the conductive patterns 28 and 30. The driver IC 24 is positioned so that the outer lead 28a overlaps with the predetermined conductive pattern 18 via the anisotropic conductive film 22, and the overlapping portion is heated and pressed to be electrically connected.
[0031]
The liquid crystal cell 10 is connected to the outer leads of the driver IC through an anisotropic conductive film also on the conductive pattern connected to the gate electrode line (not shown).
[0032]
When each driver IC is electrically connected to the liquid crystal cell 10, the insulating film 26 is bent and fixed to the glass substrate 12 at the intermediate portion of the lead. However, in the inspection method according to the present invention, the liquid crystal cell 10 is not subjected to the bending process. Is supported on the liquid crystal cell support 20.
[0033]
Reference numeral 34 denotes a pick-up coil in which a conducting wire is wound in an annular shape. The pick-up coil 34 is arranged in accordance with the dimensions of the electrical connection portion by the anisotropic conductive film 22, that is, the width and spacing of the leads 28a, The diameter of the wire, the diameter of the coil, and the number of turns are set, and a high-frequency magnetic field is generated by supplying a high-frequency current, and also serves as a high-frequency magnetic field generating means for supplying the generated high-frequency magnetic field to the electrical connection portion. A connection state with a circuit including the capacitive circuit element, that is, a connection state of an electrical connection portion where the conductive pattern 18 and the outer lead 28a are electrically connected is detected. Reference numeral 36 denotes a resonance capacitor connected in parallel with the pickup coil 34, and 38 denotes a high-frequency power source whose frequency can be adjusted. The high-frequency current is supplied to the parallel circuit of the pickup coil 34 and the resonance capacitor 36. Reference numeral 40 denotes a current detection resistor for detecting the current value of the high-frequency current supplied from the high-frequency power supply 38 to the pickup coil 34. Reference numeral 42 denotes a pickup coil support that supports the pickup coil 34. The height position of the resistor can be adjusted. The space | interval of the coil 34 and an electrical connection part can be set.
[0034]
Reference numeral 44 denotes an A / D conversion circuit that amplifies a high-frequency current flowing through the current detection resistor 40, that is, a high-frequency voltage appearing at both ends of the resistor 40, and converts an analog value into a digital value, and 46 analyzes a change in the digitized high-frequency current. And the connection quality determination part which determines the quality of the connection of an electrical connection part is shown.
[0035]
Below, the non-contact test | inspection method of the electrical connection part using this apparatus is demonstrated. First, as a result of confirming the operation by connecting the source driver IC 24 and the gate drive IC (not shown), the standard liquid crystal in which the liquid crystal cell 10, the driver IC, and all of the electrical connection portions of the liquid crystal cell 10 and the driver IC are determined to be good. A cell (circuit board) 10 is supported on a liquid crystal cell support 20.
[0036]
Next, the electrical connection portion in which the axis of the pickup coil 34 is arranged in parallel with the surface of the liquid crystal cell 10 and the conductive pattern connected to the electrode line (source electrode line or gate electrode line) and the lead 28a of the driver IC are connected. The pickup coil support 42 is lowered and the pickup coil 34 is brought close to the electrical connection portion.
[0037]
Then, a high-frequency current is passed through the pickup coil 34 to change the frequency, which is determined by the inductance of the coil 34, the capacitance of the resonant capacitor 36, the capacitive circuit element in the liquid crystal cell 10 that is mutually inductively coupled, the interelectrode capacitance of the driver IC, and the like. Tune to the resonance frequency. This adjustment operation is performed on each of the electrical connection portions connected to the source electrode line and the gate electrode line.
[0038]
When this adjustment operation is completed, the frequency of the high-frequency current supplied to the pickup coil 34 is set on each of the source electrode line side and the gate electrode line side, and the pickup coil 34 is set to a certain height with respect to the electrical connection portion. Set and move relative at a constant speed. Actually, the height position of the pickup coil 34 is fixed, the frequency of the high-frequency current to be supplied is set, the liquid crystal cell support 20 is moved in one direction at a constant speed, and the data on the source electrode line side is acquired. The direction of the coil 34 is rotated by 90 degrees, the frequency of the high-frequency current to be supplied is reset, and the liquid crystal cell support 20 is moved at a constant speed in a direction orthogonal to obtain data on the gate electrode line side.
[0039]
The electrode lines in the liquid crystal cell 10 and the lead of the driver IC have an inductance component, and have capacitance components between each electrode of the thin film transistor, between the liquid crystal of the transparent conductive film and the pixel electrode, and between the output terminals of the driver IC. The parallel circuit constituted by the inductance component and the capacitance component and the resonance circuit constituted by the pickup coil 34 and the resonance capacitor 36 include the conductive pattern 18, the anisotropic conductive film 22, and the outer lead 28a as shown in FIG. When mutual inductive coupling is performed between the stacked electrical connection portion and the pickup coil 34, a part of the current flowing through the pickup coil 34 is absorbed by the parallel circuit, and the current flowing through the resistor 40 changes depending on the connection state of the parallel circuit. .
[0040]
For example, in the case of XGA specifications, the wire diameter is 0.2 mm, the coil diameter is 0.8 mm to 2 mm, and the number of turns is 0 (straight and no winding) to 4 in the case of the liquid crystal cell 10. A high frequency current having a frequency range of 80 MHz to 1500 MH is supplied from a high frequency power supply 38 having a power supply of several mW. When a coil with a coil diameter of 2 mm and a number of turns of 2 is used, one electrical connection can be identified at a resonance frequency of 200 to 400 MHz. However, to increase the resolution, the coil diameter is reduced and the coil is made thinner. Therefore, it is desirable to reduce the number of turns and increase the resonance frequency.
[0041]
The resonance frequency of the pickup coil 34 is obtained by a liquid crystal cell determined in advance as a non-defective product, the pickup coil 34 is relatively moved on each electrical connection portion, and the voltage across the current detection resistor 40 is digitally converted by the A / D conversion circuit 44. Record digitized data.
[0042]
Next, in the manufacturing process of the liquid crystal cell 10, the liquid crystal cell 10 to be inspected to which the driver IC 24 is connected is supplied onto the liquid crystal cell support 20.
[0043]
Then, the oscillation frequency of the high frequency power supply 38 is set to a resonance frequency preset in the standard liquid crystal cell, the height position of the pickup coil 34 and the relative movement speed are set, and the pickup is performed on the electrical connection portion of the liquid crystal cell 10 to be inspected. The coil 34 is moved relatively.
[0044]
The above operation is performed on each electrode line of the liquid crystal cell 10 to be inspected, and the voltage across the resistor 40 is digitized by the A / D conversion circuit 44 and recorded.
[0045]
A digital signal obtained by detecting the digitized state of the electrical connection portion of the standard liquid crystal cell 10 with the pickup coil 34 is set as standard data 1, and a digital signal indicating the electrical connection state of the liquid crystal cell 10 to be inspected is data 2 to be inspected. And When the data 1 is displayed as a waveform, as shown in FIG. 4A, the driver IC region protrudes at three locations in the illustrated example, and concave portions 48d and 48e that are depressed between the respective convex portions 48a, 48b, and 48c, that is, between the driver ICs. The formed uneven shape.
[0046]
When the upper end portion of the convex portion showing the driver IC area, in the illustrated example, the upper end portion of the convex portion 48a is enlarged, fine irregularities 49a and 49b continue as shown in FIG. 4B. Between the electrical connection portions, the electrical connection portion and the fine concave portion 49b are shown.
[0047]
The convex portions 48a, 48b, and 48c have different heights and waveforms and are not uniform. This is because each capacitive circuit element in the liquid crystal cell 10 is affected by an adjacent capacitive circuit element, and the electrical connection between the liquid crystal cell 10 and the driver IC 24 includes many power lines, ground lines, etc. in addition to electrode lines and output lines. This is due to the presence of electrical connections.
[0048]
The data to be inspected 2 of the liquid crystal cell to be inspected may include a defective part such as a connection failure or a short circuit with an adjacent electric connection part in the electrical connection part. It is almost the same as 4 (a), and it cannot be judged from the waveform of FIG. 4 (a). Further, even in the waveform of FIG. 4B in which the state of the electrical connection portion is enlarged, the poorly connected portion has a difference in the depth of the fine concave portion 49b and the height and the waveform of the convex portion 48a vary. Whether or not the electrical connection portion is connected cannot be determined only from the depth of 49b.
[0049]
Therefore, the A / D converted digital data is processed by the connection quality determination unit 46 to determine the quality of the electrical connection unit. Processing steps inside the connection pass / fail judgment unit 46 will be described below.
[0050]
(Step 1) The standard data 1 is subjected to discrete Fourier transform. Since the standard data 1 includes noise due to the moving speed of the pickup coil 34, the frequency of the high frequency magnetic field, and the like, the low frequency region and the high frequency region of the spectrum subjected to discrete Fourier transform include noise. Therefore, unnecessary low frequency noise and high frequency noise are removed by filtering the data subjected to discrete Fourier transform. This is stored in the memory as molding standard data 1s.
[0051]
FIG. Large undulation in which the continuous fine irregularities 49a and 49b shown in FIG. Is the molding standard data 1s Since the waveform is removed and flattened, even if the shapes of the convex portions 48a, 48b, and 48c change variously as shown in FIG. The molding standard data 1s is It becomes a uniform flat fine undulation waveform, and shows the position of the electrical connection part and the coupling state of the pickup coil 34 at that position and the parallel circuit connected to the electrical connection part Will be .
[0052]
This molding standard data 1s is registered in a database for each model of the liquid crystal cell 10, so that once the model of the liquid crystal cell to be inspected is determined, it can be taken out from the database and used immediately.
[0053]
(Step 2) Discrete Fourier transform is performed on the data 2 to be inspected. Since the discrete Fourier transformed data includes low frequency ripples and high frequency noise in the spectrum, unnecessary noise is removed from the discrete Fourier transformed data and stored in the memory as the data to be inspected 2u. .
[0054]
(Step 3) The difference between the molding standard data 1s obtained in Step 1 and the molding inspection data 2u obtained in Step 2 is recorded in the memory as difference data 3.
[0055]
(Step 4) When the difference data 3 obtained in Step 3 is subjected to inverse discrete Fourier transform, determination data 4 is obtained. When this determination data is displayed as a waveform, the waveform shown in FIG. That is, when the amplitude is almost the same (the amplitude difference is small) at the corresponding electrical connection position of the molding standard data 1s and the molding inspected data 2u, the judgment data 4 has an intermediate amplitude waveform 50a. 5 is greatly different from the intermediate amplitude as shown in FIG. 5B, and when the amplitude of the molding inspected data 2u is much larger than the molding standard data 1s, the amplitude is larger than the intermediate amplitude. When the waveform 50b is obtained and the amplitude of the molding inspected data 2u is much smaller, the waveform 50c is smaller than the intermediate amplitude.
[0056]
(Step 5) The position of the driver IC and its electrical connection portion is known from the waveform position of the determination data 4, and the connection state of the electrical connection portion is known from the amplitude of the waveform.
[0057]
That is, when the display waveform of the determination data 4 exceeds the upper limit amplitude Lu shown in the figure, it is determined that the short circuit is defective, and when the display waveform is less than the lower limit amplitude Ld, it is determined that the open is defective. Can be specified.
[0058]
In this way, the connection pass / fail determination unit 46 obtains the determination data 4 by executing the processing of each step, and can determine the driver IC having a poor connection and the outer lead position from the data 4.
[0059]
When the next liquid crystal cell to be inspected is the same model as the standard liquid crystal cell, the above-described steps 2 to 5 are repeated to check the quality of the electrical connection portion.
[0060]
As described above, in the present invention, whether or not the electrical connection portion is connected is determined by flowing the pickup coil 34 and the parallel circuit including the capacitive circuit element through the pickup coil 34 without energizing the driver IC 24 and the liquid crystal cell 10. Since it is detected as a change in the high-frequency current, it can be inspected in a non-contact manner, and the quality of conduction such as a short circuit and an open circuit can be reliably detected.
[0061]
In addition, it is not necessary to bend and fix the driver IC 24 to the liquid crystal cell 10 in order to inspect the electrical connection state, and immediately after the driver IC 24 is electrically connected to the liquid crystal cell 10, it is determined whether the electrical connection is good or bad. can do.
[0062]
In order to collect data for this inspection, it is only necessary to relatively move the pickup coil 34 on the electrical connection portion, so that a special inspection position is not required, and the device of the present invention is attached to the connection process of the driver IC or its adjacent portion. Can be inspected.
[0063]
In addition, since the driver IC can be inspected without being bent, it is easy to replace the driver IC determined to be defective, and it is possible to inspect at low cost without erroneously making an undesired portion defective during replacement.
[0064]
Also, the digitized data 2 to be inspected and data-processed determination data 4 can be used as quality control data by being recorded and stored in a memory.
[0065]
FIG. 6 shows another example of the non-contact inspection method and the non-contact inspection apparatus according to the present invention. In the figure, the same parts as those in FIG. 1 differs from the apparatus shown in FIG. 1 in that a pickup coil denoted by reference numeral 51 is arranged such that the axis of the coil is vertically arranged with respect to the circuit board 10 and moved on the electrical connection portion. The pickup coil 34 of FIG. 1 arranged in parallel with the substrate (liquid crystal cell) 10 is greatly different.
[0066]
The pickup coil 34 of FIG. 1 and the pickup coil 51 of this embodiment are the same in that a magnetic field that circulates around the coil conductor is formed, but only a part of the pickup coil 34 intersects the electrical connection portion in FIG. Although the utilization factor is extremely low, the pickup coil 51 can supply most of the magnetic field to the electrical connection portion. Therefore, the diameter of the pickup coil can be reduced or the number of turns can be reduced. The sensitivity of the pickup coil 51 can be increased, and the resolution can be increased by driving the coil at a higher frequency, and detection can be sufficiently performed even if the width of the electrical connection portion and the arrangement interval are reduced.
[0067]
Further, as shown in FIG. 7, a coil 51 is wound around a connecting yoke in which a pair of rod-shaped yoke pieces are coupled to both ends of a U-shaped yoke piece or a “C” -shaped yoke 52, and the opposing surface of the yoke 52 is wound. The yoke and the liquid crystal cell 10 may be moved relative to each other by arranging an electrical connection portion of the liquid crystal cell 10 therebetween.
[0068]
Thereby, a magnetic circuit can be formed, magnetic flux leakage can be reduced, and the magnetic field can be converged on the electrical connection portion.
[0069]
In this case, by forming a concave spherical surface 52a as shown in FIG. 8 on the end face of the yoke 52 opposed via the electrical connection portion, the magnetic field between the yoke end faces is changed between the yoke end faces as shown by the dotted lines in the figure. The magnetic field can be focused on the electrical connection by concentrating on the shaft portion. Thereby, even if the diameter of the pickup coil 51 is large, the cross-sectional area of the magnetic field on the electrical connection portion can be reduced, so that the detection resolution of the adjacent electrical connection portions can be increased.
[0070]
In the above-described FIG. 1, FIG. 6, FIG. 7 embodiment, the frequency of the high-frequency magnetic field can be set in the range of 80 MHz to 1500 MHz according to the width and interval of the electrical connection portion. Further, the facing distance between the pickup coils 34 and 51 and the electrical connection portion on the substrate 10 may be in contact with each other if it is narrow, and if it is wide, the detection sensitivity is lowered. Further, the relative movement speed between the pickup coil and the electrical connection portion is preferably 5 mm / S to 30 mm / S because it takes time for processing if it is slow, and the accuracy of detection decreases if it is fast.
[0071]
The present invention is not limited to the above embodiment. For example, the circuit board is not limited to a liquid crystal cell, and a circuit board in which a large number of capacitive circuit elements such as an organic EL substrate are arranged in a matrix. It can also be applied to general circuit boards in which capacitive circuit elements are mounted on a wiring board.
[0072]
Further, the high-frequency magnetism generating means and the pickup coil are used as a single coil, but the high-frequency magnetism generating coil and the pickup coil can be provided separately. The magnetism generating coil and the pickup coil can be arranged close to each other.
[0073]
In addition to forming a concave spherical surface on the yoke end face in order to improve the convergence of the magnetic field, a groove having a V-shaped or U-shaped side cross-section may be formed, and the side cross-sectional shape of the yoke may be V-shaped. A narrow yoke tip may be disposed along the electrical connection.
[0074]
Furthermore, the electrical connection part is divided into a plurality of parts in the length direction, the pickup coil is moved relative to each divided area, the quality of the connection of the entire electrical connection part can be inspected, and the reliability of the inspection can be improved. it can.
[0075]
【The invention's effect】
As described above, according to the present invention, whether or not the electrical connection portion on the circuit board is connected can be reliably detected in a non-contact manner such as a short circuit and an open circuit without energizing the circuit board. it can.
[0076]
Also, after connecting the lead of the electronic component to the circuit board, it is possible to immediately determine whether the electrical connection is good or bad.
[0077]
Data collection for this inspection requires only a relative movement of the pick-up coil on the electrical connection part, so that no special inspection position is required, and the apparatus of the present invention is attached to the electronic component connection process or its adjacent part. Can be inspected.
[0078]
In addition, it is easy to replace an electronic component whose electrical connection is determined to be defective, and it can be inspected at a low cost without erroneously making an undesired portion defective during replacement work.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a non-contact inspection apparatus for electrical connection according to the present invention.
FIG. 2 is an enlarged perspective view of a main part showing an electrical connection part.
FIG. 3 is a circuit diagram showing a coupling state between a pickup coil and an electrical connection portion of the device of the present invention;
[Fig. 4] Detection waveform diagram on pickup coil
FIG. 5 is a waveform diagram of judgment data.
FIG. 6 is a side sectional view showing another embodiment according to the present invention.
7 is a side view of an essential part showing a modification of the embodiment in FIG. 6;
8 is a side view of an essential part showing a modification of the embodiment in FIG. 7;
[Explanation of symbols]
10 Circuit board (liquid crystal cell)
12 Insulating substrate
18 Conductive pattern
22 Conductive adhesive
24 Electronic components
34 Pickup coil
40 resistance
40 Resistance for current detection
42 Pickup coil support
46 Connection quality judgment unit

Claims (9)

Relative movement across the electrical connection, connected in parallel with the resonant capacitor, connected in series with the current detection resistor, and equipped with a pickup coil that detects high-frequency current,
A conductive adhesive for the conductive pattern of a circuit board which is a liquid crystal cell or an organic EL substrate in which a large number of capacitive circuit elements are connected in parallel and arranged in parallel on an insulating substrate and a conductive pattern is connected to one end of the circuit element. A step of bringing the high-frequency magnetic field generating means and the pickup coil for inspection close to the electrical connection portion that electrically connects the leads of the electronic component via
Analyzing the high-frequency current flowing through the pickup coil from the voltage across the current detection resistor, and determining whether or not the electrical connection portion is connected.
The step of determining whether the connection is good or bad
Discrete Fourier transform of the standard data detected by the pickup coil in the state of the electrical connection portion of the standard circuit board, removing low frequency noise and high frequency noise, and storing as molding standard data;
Discrete Fourier transform the data to be inspected, which is detected by the pickup coil, the state of the electrical connection portion of the circuit board to be inspected, removing low-frequency noise and high-frequency noise, and storing as molding inspected data;
Obtaining the determination data by performing inverse discrete Fourier transform on the difference between the molding standard data and the molding inspection data, and determining the electrical connection state from the amplitude of the waveform of the determination data;
Non-contact inspection method for electrical connections including   2. The electrical connection according to claim 1, further comprising the step of arranging the electrical connection portions in parallel at predetermined intervals along the periphery of the insulating substrate and relatively moving the high-frequency magnetic field generating means and the pickup coil across the electrical connection portion. Non-contact inspection method for connecting parts.   The non-contact inspection method for an electrical connection part according to claim 2, further comprising a step of moving the high-frequency magnetic field generating means and the pickup coil relative to the electrical connection part at a constant interval.   The non-contact inspection method for an electrical connection part according to claim 2, further comprising a step of relatively moving the high-frequency magnetic field generating means and the pickup coil at a constant speed with respect to the electrical connection part. A liquid crystal cell in which a large number of capacitive circuit elements are connected in parallel and arranged on an insulating substrate, and a conductive pattern connected to one end of the circuit element is electrically connected to a lead of an electronic component via a conductive adhesive. Or a circuit board support that supports a circuit board that is an organic EL substrate;
A magnetism generating means for generating a high-frequency magnetic field and moving relative to the conductive pattern on the circuit board and the electrical connection portion of the electronic component;
A pick-up coil that moves relative to the magnetic connection means together with the magnetism generating means, is connected in parallel with a resonance capacitor, is connected in series with a current detection resistor, and detects a high-frequency current;
A connection pass / fail judgment unit for judging the pass / fail of the electrical connection by analyzing the high-frequency current flowing through the pickup coil from the voltage across the current detection resistor ;
The connection quality determination unit
Discrete Fourier transform the standard data detected by the pickup coil for the state of the electrical connection part of the standard circuit board, remove low frequency noise and high frequency noise, and store it as molding standard data,
Discrete Fourier transform of the data to be inspected, which is detected by the pickup coil to detect the state of the electrical connection portion of the circuit board to be inspected, removes low frequency noise and high frequency noise, and stores it as molding inspected data.
A non-contact inspection device for an electrical connection part that obtains determination data by performing inverse discrete Fourier transform on the difference between the molding standard data and the molding inspected data, and determines the electrical connection state from the amplitude of the waveform of the determination data .   6. The non-contact inspection apparatus for an electrical connection part according to claim 5, wherein the pickup coil also serves as a high-frequency magnetic field generating means.   6. The non-contact inspection device for an electrical connection part according to claim 5, wherein magnetic field converging means for converging the high frequency magnetic field on the electrical connection part is disposed between the high frequency magnetic field generating means and the electrical connection part.   6. The non-contact inspection apparatus for an electrical connection part according to claim 5, wherein a magnetic circuit for circulating a high frequency magnetic field from the high frequency magnetic field generating means through the electrical connection part to the pickup coil is disposed.   The non-contact inspection device for an electrical connection part according to claim 5, wherein the conductive adhesive constituting the conductive connection part is an anisotropic conductive film or an anisotropic conductive paste.

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