JPS60216493A - Method of inspecting electrode bond of el display panel - 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 (Technical Field of the Invention) The present invention relates to a method for inspecting the quality of electrical connections between each electrode group of a thin film AC EL display panel and a substrate portion on which a driving circuit is mounted.

(Technical Background) Display panels with various structures have been proposed in the past, but Figure 1 is a partial diagram showing the bonding state between a thin film AC EL display panel with a double insulating layer structure and a printed wiring board section. FIG.

As is clear from this figure, this panel is connected to this board 1.
A large number of transparent electrode groups 2 are provided in M rows in the lateral direction on top, and a dielectric layer 3 made of Y, 03, Sin, or other material is provided above them.
and 5, a light emitting layer 4 made of ZnS is sandwiched between them, and a large number of back electrode groups 6 made of metal are provided on this dielectric layer 5 in N rows in a direction intersecting with the transparent electrode group 2. It has a similar structure.

In this case, the lead terminals of the transparent electrode group 2 and the back electrode group 6 are connected to the solder surfaces 88 to 8f of the printed transparent electrode side substrate part 7a and the back electrode side board part 7b (for example, a flexible cable) using, for example, a laser beam. For soldering, a device is used to perform soldering and joining, and then these joining surfaces are fixed with an adhesive to improve mechanical strength.

However, these joints may have poor soldering, and conventionally, a tester or an alternative inspection method is used to
The quality of the electrical connections was inspected for each electrode, but since there were a large number of electrodes, the inspection was time consuming, and moreover, inspection errors occurred.

(Objective of the Invention) An object of the present invention is to enable accurate testing in a short time even if the number of electrodes to be tested increases, and to ensure that the electrodes to be tested are fit
It is an object of the present invention to provide a method for inspecting an electrode joint portion of an EL panel, in which inspection is performed by effectively utilizing a drive circuit mounted on an L panel unit.

(Structure of the Invention) In order to achieve this object, according to the present invention, each lead of a transparent electrode group and a back electrode group are provided to sandwich a capacitive element constituting a thin film AC EL display panel and intersect with each other. When inspecting the quality of the bond between the terminal section and the transparent electrode side substrate section and the back electrode side substrate section, each of which has a drive circuit, the drive circuit is operated to inspect the transparent electrode group and the back side substrate section. A test voltage signal is sequentially applied to each electrode to be inspected in one of the electrode groups via the electrode junction corresponding to this electrode to be inspected, and the voltage signal in the other electrode group is applied in response to this voltage signal. detecting a measurement voltage signal induced in any one of the specified electrodes, and comparing the voltage level of this measurement voltage signal with a preset threshold voltage;
When this voltage level is equal to or smaller than a threshold voltage, the electrode junction is determined to be defective.

(Explanation of Examples) Embodiments of the present invention will be described below with reference to the drawings.

This invention takes advantage of the fact that each electrode group of an AC EL display panel is configured in a matrix and each electrode intersection is capacitively coupled, and by sequentially applying a pulse signal to one electrode group, an induced signal is generated to the other electrode group. The purpose is to inspect the electrical connection state of the electrode junction portion based on the potential level value of the pulse waveform train.

First, a test circuit for carrying out the test method will be described with reference to FIG.

FIG. 2 is a block diagram showing an example of a test circuit. 10
1 shows an EL display panel unit equipped with electrodes to be inspected, which includes an EL display panel 11, a transparent electrode side substrate part 7a having a drive circuit 12a on the transparent electrode group 2 side arranged in the X direction, and Drive circuit 1 on the side of the arrayed back electrode group 6
2b, and these substrate parts 7a and 7b have a solder surface 8a and a
It is joined to each electrode group 2 and 6 of the EL display panel 11 by soldering at ~8f. The lead terminals of this EL display panel have undergone initial inspection for disconnections and short circuits for each panel, and the drive circuits 12a and 12b have also been inspected and are in perfect condition. The EL display panel unit 10 shown in 2 has a completely commercial-grade configuration.

Assuming that this EL display panel 11 has a pixel count of MXN,
Driver circuits 13a, 13b and latch circuits 14a, 14 are provided on the transparent electrode side substrate section 7a and the back electrode side substrate section 7b.
b and shift registers 15a, 15b are mounted.

Inspection terminals (inspection positions) 10b and 10a are led out from the transparent electrode group 2 and back electrode group 6 sides of this EL display panel unit 10 by any conventional method, respectively, or
These test terminals may be formed on the EL display panel unit 11 in advance. This terminal 10a is from an arbitrarily selected electrode n on the back electrode side when inspecting the bonding state on the transparent electrode side, and the terminal 10b is from the transparent electrode when inspecting the bonding state on the back electrode side. from any selected electrode m on the side, each of which is taken as an inspection position.

The test circuit that actually performs the test operation on the EL display panel 11 to be tested consists of an automatic changeover switch 16 and an A/D' converter 4.
? Wt7, personal computer 18, and control unit 1
8.

During inspection, the automatic changeover switch 16 connects the fixed terminals 1[1a and 16h, which are connected to the test terminals 10a and 1ob respectively and receive measurement voltage signals, and the fixed terminals lea and +eb, from transmitting signals from a personal computer to be described later. It has a switching contact lec that switches according to a command, and this switching contact 18c is grounded via a sampling resistor R. The A/D converter 17 is connected to this switching contact +6c.
The analog measurement signal from the converter is converted into a digital signal and supplied to the personal computer 18. The control section 19 operates based on instructions from the computer 18 and controls the internal board section 7.
It mainly supplies start pulses and clocks to a and 7b, and supplies a sample clock to the A/D converter 17. The A/D converter 17 converts the analog measurement signal into a digital measurement signal in synchronization with this sample claw 2,
Output to computer 18.

Next, Fig. 3 (A) and CB) and Fig. 4 (A), (B)
) and (C), the principle of the method according to the invention will be explained.

FIG. 3(A) shows an equivalent circuit of a circuit under test when the electrical connection at the junction is good, and FIG. 3(B) shows an equivalent circuit of a similar circuit under test when the electrical connection is defective. In these figures, C
is the equivalent capacitance of the EL display panel during inspection and measurement, Ro
is an isometric resistance when each driver circuit 13a or 13b on the inspection position side is in the off state, and R5 is a sampling resistor, one end of which is grounded and the other end connected to the A/D converter 17. . Also, there is a relationship of Ro)) Rs. Vc is a voltage signal source for inspection. Furthermore, the part shown within the broken line in Fig. 3(B) is the equivalent circuit of the part that causes an impedance change when the electrical connection of the joint to be inspected is defective, and the resistance RN (RN) R5) and the capacitance are CN CC
It can be expressed as a parallel circuit with N<<C).

As is clear from this figure, impedance changes in the case of a poor junction, so it is sufficient to extract this change in impedance as a voltage change.

For example, in this equivalent circuit, first select the first electrode of the driver circuit +3a on the transparent electrode side and
) is applied to this electrode, and all other unselected electrodes are placed in a floating state. In this state, the pulse voltage V applied from the transparent electrode side is capacitively coupled and passes through the designated electrode n, which is the inspection position on the back electrode side, to the inspection terminal 10a.
is induced as a measurement voltage signal X shown in FIG. 4(B). The waveform of this measured voltage signal X is obtained as a voltage waveform as shown in a of the same figure when the junction is good, and as a voltage waveform as shown in b when it is defective. As is clear from this figure, when the connection of the electrode to be inspected is normal, the voltage level of the measurement voltage signal a is X, and when it is defective, the voltage level of the measurement voltage signal A is x2, and It can be seen that it is smaller compared to . Therefore, by selecting the pulse period T of the pulse voltage V to be sufficiently smaller than the time constant of the measurement equivalent circuit, the quality of the junction can be detected as a difference in voltage levels.

Therefore, a threshold voltage K for pass/fail judgment is set in advance in the personal computer, and the voltage level of the measured voltage signal X extracted at the timing of the sample clock as shown in FIG. Conversion After conversion, the voltage level (
(also represented by X) and the threshold voltage, K
It is possible to determine the quality of the joint, such as if it is normal if <x, and if K≧X, it is defective. And this test
For example, each electrode may be sequentially scanned.

Next, an inspection method according to the present invention based on such a principle will be explained with reference to the inspection circuit of FIG. 2 and the flowchart of FIG. 5.

FIG. 5 is an inspection flowchart showing an example of an inspection procedure for inspecting the quality of soldering of the electrode lead terminal to the substrate portion.

The test circuit is connected to the EL display panel unit 10, and testing is started as shown in step 20. First, it is assumed that the joint portion on the side of the transparent electrode group 2 is inspected.

First, in step 21, a threshold voltage K is set in the computer 18. Next, in step 22, the electrode number (line number) of the line counter of the computer 18 is
Set Xm to 1. Subsequently, the test circuit is operated, and the control section 18 supplies one start pulse and a clock to the drive circuit 12a of the substrate section 7a according to a command from the computer 18, and the first address is designated to set the electrode number. A transparent electrode with Xm=1 is selected, and transparent electrodes other than the selected electrode are placed in a floating state. At this time, the switching contact 18c of the automatic changeover switch 16 is switched to the fixed contact 16a side according to a command from the computer 18.

In this state, an inspection voltage signal (pulse voltage) ■ is applied to the transparent electrode with electrode number 1 by the driver circuit 13a, and in response, a measurement voltage signal X induced on the back electrode n is obtained at the fixed contact 18a. It will be done. In step 23,
This voltage level X is extracted and measured using a sample clock, and the measured voltage level X is supplied to the computer 18 via the A/D converter 17.

Then, in step 24, the supplied measured voltage level
is input into the computer 18, where this voltage level X is compared with an internally set threshold voltage. If K<x, the process moves directly to the next step 25, but if K≧X, the electrode number X of the defective connection is determined in step 26.
m (specified by the line counter), in this case the electrode number l, is stored in a register for connection failure in the computer 18, and then the process moves to step 25. This completes the inspection of − electrodes.

Next, in step 25, the electrode number Xff1 of the line counter is updated by 1, and becomes Xm+1, that is,
Set electrode number 2, supply a clock from the control unit 18 to the drive circuit 12a according to a command from the computer 18,
The transparent electrode with electrode number 2 is selected and the next pulse voltage V is supplied to it, and the bonding quality of this electrode is inspected in the same manner as described above. In this way, all the transparent electrodes of M lines are sequentially inspected, and the electrode number of the defective connection is stored in the register.

Next, in step 27, it is checked whether or not the - cycle inspection has been completed, and if it has not been completed, the process returns to step 23, and the inspection is continued in the same way, and if it has been completed, the A similar test is started for the electrode group 6.

First, in step 28, the electrode number Yn of the line counter is set to 1, the switching contact 18c of the automatic changeover switch 16 is switched to the fixed terminal 16b, and the testing operation is started at the testing position iob.

In step 28, the voltage level If it is determined that the connection is defective, the process moves directly to the next step 31. If it is determined that the connection is defective, the electrode number Yn is stored in the register in step 32, and then the process moves to step 31. This completes the inspection of - back electrodes.

Subsequently, in step 31, the electrode number of the line counter is updated to Yn+1 and a similar test operation is performed, and in this way, all back electrodes of N lines are sequentially tested.

In this case as well, in step 33, it is checked whether or not the - cycle inspection has been completed, and if it has not been completed, the process returns to step 29, and the inspection is continued in the same way, and if it has been completed, step At step 34, the electrode number of the defective connection stored in the register is displayed on a display or other means.

If there is a bonding defect, step 35 to step 2
Returning to step 2, in step 36, each electrode with the displayed electrode number is repaired by the soldering device, and then returned to its original state, and re-inspection is repeated until there are no defective parts.

If there is no defective bonding, the inspection ends at step 37.

As is clear from the above description of the test procedure, the personal computer 18 used here has the functions of starting the test procedure, setting a threshold voltage and comparing this with the measured voltage level, It has a function to store comparison results, a function to sequentially specify electrode numbers, a function to judge the end of -cycle inspection, a function to issue an automatic changeover switch switching command, and a function to display the contents of the register on an external display means. It mainly has the function of displaying information.

In addition to the start pulse, clock, and sample clock described above, the control unit 19 also includes a drive circuit 12a.

Of course, it also generates the signals necessary to operate +2b.

(Effects of the Invention) As is clear from the above description, the method for inspecting the electrode joints of an EL display panel according to the present invention requires that each electrode group of an AC EL display panel is configured in a matrix and that each electrode intersection point is This is a method that takes advantage of capacitive coupling and also makes effective use of the drive circuit installed in a commercial-grade EL display panel unit. Since the electrical connection state of the electrode junctions is automatically tested sequentially based on the voltage level of the measurement voltage signal induced in the electrodes of the other electrode group when a signal is applied, the number of electrodes increases. It has the advantage that it can be inspected accurately and in a short amount of time.

[Brief explanation of the drawing]

Fig. 1 is a partial perspective view for explaining the structure of a double insulated thin film EL panel and the electrical connection with the printed wiring board section, and Fig. 2 is a block diagram for explaining the test circuit used in this invention. Figure 3 (A) and (B) are diagrams showing the equivalent circuit of the circuit under test when the junction is good and when the junction is bad. Figure 4 (A) to (C) are the test voltages. FIG. 5 is an inspection flowchart for explaining the procedure of the joint inspection method according to the present invention. 1... Glass substrate, 2... Transparent electrode group 3.5...
・Dielectric layer, 6...Back electrode group 7a...Transparent electrode side substrate part, ? b...Back electrode side substrate portion 88-8f...
・Solder surface 10... EL display panel units 10a, 10b... Inspection terminal (inspection position) 11...
- EL display panel 12a... (transparent electrode side) drive circuit 12b... (
(on the back electrode side) drive circuits 13a, 13b...driver circuits 14a, 14b...latch circuits 15a, 15b...shift register 16...automatic changeover switch LEA, +6b...fixed terminal, 18c... - Switching contact 17... A/D converter 18... Personal computer 18... Control section. Patent Applicant Oki Electric Industry Co., Ltd. Procedural Amendment April 6, 1985 2 Name of Invention Method for Inspecting Electrode Joints of EL Display Panels 3 Person Who Makes Amendment Relationship to Case Patent Applicant Address 1-105) 1-7-12 Toranomon, Minato-ku, Tokyo Name (02'9) Oki Electric Industry Co., Ltd. Representative Nankai Hashimoto 4 Agent Address 1-20-5 Ikebukuro, Higashiikebukuro, Toshima-ku, Tokyo 170 县 (988) 5583 Detailed description of the invention in the specification of House Bill No. 905, contents of the amendments to Figure 4 (A) of the drawings and Figure 5 of the drawings 7 As attached (1), specification, page 7, line 10 "Via resistance R"
is corrected to "via resistor Rs." (2), same, page 10, line 11, "based on" is corrected to "based on". (3) Correct the 9th drawing, Figure 4 (A), as shown in the attached correction diagram. (4) Correct Figure 5 of the 8th drawing as shown in the attached correction diagram. Procedural Amendment May 15, 1985 Mr. Manabu Shiga, Commissioner of the Patent Office 1 Case Indication 1989 Patent Application No. 3 No. 3 2 Name of Invention Method for Inspecting Electrode Joints of EL Display Panels 3 Amendment Case Relationship Patent applicant address (〒-105) 1-7-12 Toranomon, Minato-ku, Tokyo Name (029) Oki Electric Industry Co., Ltd. Representative Nankai Hashimoto 4 Agent 〒170 廿 (988) 5583 Address Toshima, Tokyo Figure 4 (A) of the 5th drawing, Higashiikebukuro 1-20-5 Contents of the 7 amendment As attached, (1) Figure 4 (A) of the 1st drawing will be corrected as shown in the attached corrected drawing.

Claims (1)

[Claims] A transparent electrode side substrate portion and a back electrode side each including lead terminals of a transparent electrode group and a back electrode group that sandwich a capacitive element constituting a $1 membrane AC EL display panel and intersect with each other, and a drive circuit. In inspecting the quality of the connection of each electrode joint with the substrate part, the driving circuit is operated to connect each electrode to be inspected of one of the transparent electrode group and the back electrode group. Test voltage signals are sequentially applied through the corresponding electrode junctions, and a measurement voltage signal is induced in a designated arbitrary electrode of the other electrode group in response to the voltage signals. detecting and comparing the voltage level of the measured voltage signal with a preset threshold voltage, and when the voltage level is equal to or less than the threshold voltage, the electrode junction A method for inspecting an electrode joint of an EL display panel, the method comprising determining that it is defective.