JPH02216477A - Contact inspecting method - Google Patents

Abstract

PURPOSE:To discriminate the quality of a contact by applying a square wave- like measuring signal and monitoring a response characteristic waveform at the time of inspecting whether a first and a second electric conductors are brought into contact or not. CONSTITUTION:In parallel lines connected to electrode pads 80, 82, a floating capacity C exists as a high frequency. When a square wave-like voltage (a) is applied to one of these parallel lines, a current (b) can be monitored by a size of the floating capacity C in the other electrode. Therefore, when the voltage (a) is applied to the electrode pad 80 and the current from the electrode pad 82 being adjacent thereto is monitored, and when it shows a prescribed CR curve (b), it is known that a probe needle, etc., are brought into contact correctly with both electrode pads 80, 82.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a contact inspection method.

(Prior Art) When testing the electrical characteristics of a printed circuit board or a liquid crystal display (LCD) board, probe needles or flexible printed circuits (FPC) are attached to electrode pads on the board.
) is carried out by contacting the electrodes.

Here, to take an LCD as an example, this LCD has a large number of TPTs, which are liquid crystal driving elements, arranged in a matrix, and a common source line (screen source line) in which the sources of the TPTs are wired horizontally for each column. corresponding to ), and
This line is connected to a source lead electrode provided at the lateral end of the substrate. On the other hand, the gates of the TPT for each row are connected to a common gate line (corresponding to the signal line of the screen) wired vertically, and this line is connected to the gate lead electrode provided at the vertical edge of the substrate. ing. When testing the electrical characteristics of the LCD, a probe needle or FPC is brought into contact with the source lead electrode and gate lead electrode provided at both ends of the substrate in the horizontal and vertical directions. are doing.

This test is performed by applying current from one of the above electrodes and monitoring the current output through the other electrodes, and if a predetermined monitor output is not obtained, it is determined that there is a defect. Ru.

(Problem to be solved by the invention) If there is a disconnection or short circuit in the wiring line on the board, or if there is a failure in the element itself on the board, it is determined that it is defective because an appropriate monitor output cannot be obtained. However, another case in which such an appropriate monitor output cannot be obtained is that the probe needle is not properly contacted with the electrode pad on the substrate.

Therefore, when performing the above-mentioned inspection, it should be judged as defective only when the electrode pads on the substrate are properly contacted and an appropriate monitor output cannot be obtained.

However, especially for devices with a large number of electrode pads such as LCDs, it is difficult to visually determine whether or not the contacts to the electrode pads have been made correctly. By performing an alignment operation for this purpose, it was assumed that the contact was made correctly after the alignment operation, and any device that could not obtain an appropriate monitor output was determined to be defective.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a contact inspection method that can detect the contact state of a conductor to a component.

[Structure of the Invention] (Means for Solving the Problems) The present invention applies a rectangular waveform measurement signal and measures the response characteristic waveform when inspecting whether or not the first and second conductors are properly contacted. This monitors the contact quality to determine whether the contact is good or bad.

(Function) When inspecting the contact status of conductors, if a rectangular wave measurement signal is applied to one conductor and the response waveform is monitored from the other conductor, it is determined that there is a stray capacitance between the two conductors. Therefore, if the contact is made correctly, a response waveform based on the stray capacitance is obtained, and the quality of the contact is controlled.

(Example) Hereinafter, an example in which the present invention is applied to a contact inspection method using a probing device used for checking the electrical characteristics of an LCD will be specifically described with reference to the drawings.

First, an outline of a probing device for LCD inspection will be explained with reference to FIG. 2.

In the figure, the mounting table 10 has LCDs 12 of various sizes.
It can be mounted and supported, and can be moved in the X direction, Y direction, two directions perpendicular to the X and Y axes (not shown), and the θ direction, which is the direction of rotation around the Z direction. It becomes.

The LCD 12 has electrode pads along each of its four outer sides, and therefore, this blowing device also has a structure for contacting each of the electrode pads on the four sides of the LCD 12.

First, an FPC card 20 is provided for contacting electrode pads arranged along the left side of the LCD 12 shown in FIG. This FPC card 20 is
As shown in FIG. 3, a film electrode 2 whose one end is electrically connected to an electrode pattern formed on the lower surface side of a circuit board 22
4, and the tip side of this film electrode 24 has a flexible member 2
6, and the lower surface side of this curled portion can contact an electrode pad present on the left side of the LCD 12. And this FPC card 20
is configured to have the same number of electrode pads as the total number of all electrode pads present on the left side of the LCD 12 of the minimum inch size.

The FPC card 20 is fixed at a predetermined position, but when the inch size of the LCD 12 becomes large, the mounting table 10 is moved in the Y direction so that all the electrode pads of the large-sized LCD 12 are covered. It is possible to contact them sequentially.

In order to contact the electrode pads on the upper and lower sides of the LCD 12 in FIG. 2, a first probe card 30 and a second probe card 40 each having a plurality of fixed probe needles are provided.

The first probe card 30 is movable in the X direction along the X direction guide 32, and the driving force of the first motor 34 is transferred to the driving force of the first probe card 30 in the X direction by a wire or a ball screw. This movement is made possible by converting it into .

On the other hand, the movement mechanism of the second probe card 40 is as follows. That is, the first movable base 60 is
It is movable in the X direction along the X direction guides 62, 62, and is movable in the X direction by the driving force of the second motor 64. On this first movable base 60, Y direction guides 66, 66 are provided in parallel, and this Y direction guide 66,66 is provided in parallel.
A second movable base 70 is movable along the directional guides 66,66. And the first movable base 60
The second movable base 70 is movable in the Y direction by the driving force of the third motor 68 provided above. The second probe card 40 is fixed to the second movable base 70, and the second probe card 40 is fixed to the second movable base 70. Second movable base 60
．． 70, the second probe card 40
, is movable in both the Y direction.

A common contactor 50 is fixed to the second movable base 70 for contacting the electrode bar located on the right side of the LCD 12. This common contactor 50 is configured to be able to contact all the electrode pads on the right side of the LCD 12 at once, and is constructed by arranging conductive rubber members along the Y direction in FIG. 2, for example.

In addition, the above-mentioned 1. The second probe card 30.degree. 40 and the common contactor 50 are provided with an up-down mechanism so that they can be switched between a contact state and a non-contact state with respect to the electrode pads of the LCD 12.

Next, a method of inspecting the electrical characteristics of the LCD 12 in the device of the above embodiment and a method of determining whether the contacts are good or bad will be explained.

The above-mentioned embodiment device allows the following tests.

■Gate Oven Test Assuming that each line extending in the Y direction of the LCD 12 shown in Fig. 2 is a gate line, the gate line open test is performed by connecting the FPC card 20 and the common contactor 50, and placing probe needles on both the left and right sides of the LCD 12. contact and
This is possible by setting the conduction state, that is, the resistance value, to 11-1.

Here, when the inch size of the LCD 12 is the minimum size, all the electrode pads existing on the left side of this LCD 12 are individually contacted by the FPC card 20, while all the electrode pads existing on the right side of the LCD 12 are contacted individually. These are collectively contacted in a short-circuited state by the common contactor 50. Therefore, for example, by selectively energizing the gate lines via each electrode pattern on the FPC card 20 side and monitoring this output with a tester via the common contactor 50, the presence or absence of disconnection in each gate line is inspected. It becomes possible.

In addition, if the size of the LCD 12 is larger than this,
By moving the mounting table 10 in the Y direction, the LCD 1
It is possible to contact both the left and right sides 1 of 2 and all existing electrode pads, and thereafter oven inspection of the gate line can be performed in the same manner.

■Drain line open test Regarding the drain lines formed along the vertical direction of the LCD 12, the first. This is possible by using a second probe card 30.40. Then, the first . In order to contact the probe needles of the second probe card 30.40, each probe card 30.40 must be
This can be achieved by sequentially moving in the direction.

■Short circuit test between gate and drain Test for short circuit at the intersection of gate and drain using FPC card 20.
This is possible by using the first probe card 30 or the second probe card 40. That is,
For example, by supplying current to the gate line through one electrode pattern of the FPC card 20 and checking whether or not the current is monitored through a probe needle that is in contact with the drain line that intersects with the gate line, the above intersection point can be detected. It is possible to detect the presence or absence of a short circuit.

In each of the above tests, if a predetermined output is not monitored by the tester, an open or short-circuit failure is determined, but this is because the FPC card 20.
1st. It is assumed that all electrode pads of the second probe card 30, 40 are properly contacted.

Therefore, in order to improve the reliability of the above inspection, it is necessary to also check whether there is a contact failure.

Therefore, in this embodiment, the FPC (or probe needle) is brought into contact with the electrode pad by the method described below, and it is determined whether each contact is good or bad. That is, as shown in FIG. 1(C), if the electrodes at one end of the parallel line are electrode pads go and 82, then this electrode pad 80°82 or the parallel line connected to it is It can be regarded as an electrode, and therefore a stray capacitance C will always exist between them at high frequencies.

Δt1 on one side of the parallel line where such a capacitance c exists
When a constant signal such as a rectangular wave voltage (see FIG. 1(A)) is applied, a current as shown in FIG. 1(B) is monitored at the other electrode depending on the magnitude of the stray capacitance C. That is, the rise characteristics deteriorate depending on the size of the stray capacitance C. This rise characteristic determines the desired allowable range of capacitance C.
Monitor and judge whether the waveform is as shown in Figure (B).

Therefore, the voltage shown in FIG. 1(A) is applied to one electrode pad 80 shown in FIG. 1(C), the current from the adjacent electrode pad 82 is monitored, and this is shown in FIG. 1(B). If the predetermined CR left curve is exhibited, the picture electrode pad 80.
It can be confirmed that the FPC and the electrode pad are in contact with each other correctly. If either one of the
If the contact to the electrode pad is poor, the same figure (
The CR left curve monitor output shown in B) cannot be obtained, and the stray capacitance c due to contact failure is superimposed, resulting in poor rise characteristics.

In this embodiment, it is determined whether the contact between the electrode pad and the FPC card 20 is good or bad based on the principle as described above. That is, in order to detect whether the contact to the electrode pad existing at the end of the gate line is good or bad, a voltage is applied from one of the adjacent electrode patterns of the FPC card 20, and the current output from the other is monitored. By doing this, it is possible to determine whether the contacts to these two electrode pads are good or bad based on the same principle as above.

By performing such a determination for each electrode of the FPC card 20, it is possible to determine whether the contact quality of all the electrodes of the FPC card 20 is good.

Defects can be identified. Such an examination is performed using a first probe having a probe needle. The same can be done for the second probe card 30.40.

Here, as a program for performing such a contact failure, two types of methods shown in FIGS. 4(A) and 4(B) can be adopted.

First, the method shown in FIG. 4(A) will be explained. In step 1), each line is inspected for openness, and whether or not it is open is determined based on the monitor output at that time (step 2). If it does not open, it is possible to immediately determine that it is a good product (step 3). On the other hand, if it is determined in step 2 that an open has occurred, a contact inspection is performed based on the principle described above (step 4). Then, it is determined whether the contact is normal or not based on the monitor output at that time (step 5), and if the monitor output exhibiting a CR left curve as shown in Fig. 1 (A) is obtained, It can be immediately determined that an open has occurred in that line (step 6). On the other hand, if it is determined in step 5 that a contact failure has occurred, contact adjustment is performed (step 7), and then the process returns to step 1 again to perform an open inspection.

In the method shown in FIG. 4(B), a contact inspection is first carried out (step 1), and whether the contact is good or bad is determined based on the output monitor at that time (step 2). If it is determined that the contact is defective, contact adjustment is performed (step 3), and the process returns to step 1 to perform the contact inspection again. If it is determined that the contact is good in step 2,
Next, an oven inspection is carried out (step 4), and the output monitor at that time is used to determine whether the oven is good or bad (step 5), and based on the results, it is determined whether the oven is good or defective (step 6.7).

Note that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention.

Although the above embodiment has been described as being applied to contact inspection for electrode pads of an LCD, the present invention is not limited to this, and can be applied to various other objects to be inspected as long as they have at least adjacent electrode pads. Furthermore, the wiring pattern is usually formed on the surface of the substrate, and its electrode pads are also arranged adjacent to each other on the surface of the substrate.
The present invention is not limited to such a case, and the present invention can be similarly applied to, for example, determining whether contact is good or bad between electrode pads that are arranged adjacent to each other in the thickness direction of a circuit board. That is, even in such a case, the adjacent electrode pads can be regarded as parallel electrodes, and there is always a stray capacitance between these parallel electrodes.

[Effects of the Invention] As explained above, according to the present invention, after a contact action, a rectangular waveform signal is applied, and the contact state can be determined from the response waveform.

[Brief explanation of the drawing]

FIGS. 1(A), (B), and (C) are schematic explanatory diagrams for explaining the present invention in detail, respectively, and FIG. 2 is an LCD blowing device to which an embodiment of the method of the present invention is applied. FIG. 3 is a schematic plan view of the FPC, and FIG. 4A is a schematic explanatory diagram illustrating the configuration of the FPC. (B) is a flowchart for explaining the flow of electrical characteristic testing including the contact detection method. 80.82... Adjacent electrode pad, C... Stray capacitance. Agent Patent attorney Inoue - (1 other person) Figure 1 (A) Figure 2 (B) ) = Thea J1 bsu (C) Kon 3 Figure

Claims (1)

[Claims] (1) In inspecting whether or not the first and second conductors are properly contacted, a rectangular waveform measurement signal is applied and the response characteristic waveform is monitored to determine whether the contact is good or not. Contact testing method.