JPS6379075A - Continuity test apparatus - Google Patents

Abstract

PURPOSE:To enhance inspection accuracy, by providing a means for detecting the contact state between the contact elements of each measuring element having two contact elements insulated each other and a means judging whether each of the contact elements contacts with a pattern to be tested. CONSTITUTION:Each of probe pins 7a, 7b is constituted so that contact elements 14l, 14r are mutually insulated by interposing an insulating material 13 to the central part thereof and selectively connected to a measuring circuit 15 and a contact detection circuit 16 through change-over switches SW1-SW4. A control apparatus 11 compares the detection value from the circuit 16 with a voltage value preset of a normal contact state and judges a normal state when both of them almost coincide to output a control signal to a switch change-over control part 17 and the switches SW1-SW4 are changed over to the side of the circuit 15 by the control part 17 to perform continuity testing processing. Continuity inspection processing is performed by comparing the measured value from the circuit 15 with the reference value between measuring points preset and judging whether an inferior place of disconnection or short-circuit is present between the measuring points. By this method, inspection accuracy can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a continuity testing device for testing, for example, wiring abnormalities on a high-density printed wiring board.

[Prior Art] In general, printed wiring boards have a pattern line width becoming narrower due to higher pattern density, and the spacing between lines also becoming narrower. The number of circuit boards is also increasing.

In such printed wiring boards, before mounting electronic components, etc., it is necessary to inspect the wiring pattern to avoid mounting electronic components, etc. on a defective board. Especially in multilayer boards, defects cannot be detected. If they are stacked on top of each other, the whole becomes defective and must be disposed of, leading to a decrease in yield and an increase in production costs. Moreover, high-density printed wiring boards are expensive, so if a defective part is found during inspection, the defective state should be corrected when it is possible to reduce costs. It is hoped that

For this reason, conventionally, optical inspection methods, capacitance measurement methods, and the like have been employed when inspecting wiring patterns such as copper foil formed on printed wiring boards for disconnections or short circuits.

Here, the optical inspection method is a method in which a light beam is irradiated onto the printed wiring board and the reflected or transmitted light is read to inspect whether or not defects such as disconnections or short circuits have occurred in the wiring pattern. It does not measure the conduction state of
There are problems in that it is not possible to detect small breaks or short circuits due to resolution, and accurate inspection cannot be performed when the surface of the printed wiring board is coated with resist or has deposits.

In addition, the capacitance measurement method measures the capacitance of the upper and lower patterns, and it is not possible to identify defective areas such as disconnections and short circuits, and a person must visually identify the defective areas. However, in high-density printed wiring boards, there is a problem in that it is difficult to visually identify defective locations.

In order to solve these problems, multi-bin continuity testing methods have been proposed. In this continuity testing method, for example, as disclosed in Japanese Unexamined Patent Publication No. 47-21082, first and second measurement point selection sections are connected to socket pins of a printed wiring board via adapters, and these measurement points are measured. The resistance determination circuit measures the conduction resistance between the two measurement points selected by the point selection section, compares and determines this with a reference value, and controls each measurement point selection section and the resistance determination circuit using the controller section. The device is configured to automatically test continuity between measurement points by analyzing information from the determination circuit.

[Problem that the invention seeks to solve]

However, the multi-pin continuity testing method described above does not have a function to detect the contact state between the socket pin of the printed wiring board and the measurement point selection section. If a contact failure occurs between the patterns, it may be incorrectly determined that the pattern to be tested is defective even though it is normal when testing the continuity state of the pattern to be tested, or when testing the resistance of the pattern to be tested. There is a problem in that the contact resistance changes and the resistance value cannot be detected accurately, and the continuity or resistance of the pattern to be tested cannot be tested with high accuracy.

Therefore, the present invention has been made by focusing on the above-mentioned problems of the conventional example, and involves determining the contact state between each probe and the pattern to be inspected before measuring the continuity or resistance value of the pattern to be inspected. Therefore, it is an object of the present invention to provide a continuity testing device that can significantly improve the testing accuracy.

[Means for solving problems]

In order to achieve the above object, the present invention provides first and second
In the continuity testing device, each measuring element has two contact points that are close to each other and insulated from each other. a contact detection means for detecting a contact state between each contact of each of the measurement probes, and a contact detection means for detecting a contact state between each contact of each of the measurement probes; The present invention is characterized by comprising a contact state determining means for determining whether or not there is a contact state. Here, the contact detection means not only detects whether current flows by passing current between the contacts, but also connects a power source to each contact via a resistor and detects the voltage between the terminals of the resistor. It also includes cases where the value of current flowing between contacts is detected.

[Effect]

In this invention, the first and second probes are composed of two contactors that are close to each other and insulated, and the contact state between them is detected by a contact detection means.

In other words, when each probe is not in contact with the pattern to be inspected, the contacts are insulated, and when they come into contact with the pattern to be inspected, the pattern to be inspected causes the contacts to be in a conductive state. By detecting it, it is possible to determine the contact state between the contact of each probe and the pattern to be inspected. In particular, if a constant voltage is applied between the contacts via a resistor with a predetermined resistance value and the voltage between the terminals of the resistor is detected, the contact state between the contacts and the pattern to be inspected can be determined more accurately. Can be done.

Therefore, the detection value of the contact detection means is supplied to the continuity determination means, and the continuity determination means determines the contact state of each contact point, and the determination result indicates that each contact point and the pattern to be inspected are in normal contact. By performing a continuity test or resistance measurement between each measuring element when the measuring element is in use, the detection can be performed with high precision.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

1 to 4 are diagrams showing one embodiment of the present invention.

In FIG. 1, 1 is a printed wiring board as a measurement object placed on a table T, 2a and 2b are first printed wiring boards, respectively.
and hold the second measuring heads 3a and 3b and move them to
This is a moving mechanism that moves in the Y direction.

Each of the moving mechanisms 2a and 2b has a cart 4 that is guided in the X direction along the side edge of the printed wiring board 1, and a U-shaped frame 5 is bridged between these carts 4 to form an X-axis moving section 6a. ,
6b is formed, and measurement heads 3a, 3b movable in the Y-axis direction are arranged in the U-shaped frames 5 of these X-axis direction moving parts 6a, 6b, and these measurement heads 3a, 3b are provided with a Z-axis direction ( Probe pins 7a and 7b are held as first and second probes that are movable in the vertical direction in the figure.

The moving parts 6a and 6b are driven by drive mechanisms 8a and 3b such as pulse motors and DC motors, and the measuring rods 3a and 3
Probe pins 7a and 7b are driven by drive mechanisms 9a and 9b, each of which is composed of a rotary drive unit such as a pulse motor or a DC motor, and a ball screw connected to this and screwed into the measurement heads 3a and 3b. Drive mechanism 10a
, 10b, and these drive mechanisms 8
a, 8b to 10a, 10b are the control device 11 shown in FIG.
Drive controlled by.

As shown in FIG. 2, each of the probe pins 7a and 7b is formed into a cylindrical shape made of a conductive material, has a conical portion 12 at its lower end, and has an insulator 13 interposed in the center thereof. The half portions are insulated from each other and serve as independent contacts 14L14r.

And each probe pin? a, 7b contacts 141.1
4r connects to the measurement circuit 15 and the contact detection circuit 16 as contact detection means via changeover switches SW and SW4, respectively.
selectively connected to.

The control device 11 is composed of a microcomputer equipped with an interface circuit, an arithmetic processing device, and a storage device, and the measured value from the measuring circuit 15 and the detected value from the contact detection circuit 16 are input to its data input side. With,
Each drive mechanism 8a, 8b, 9a, 9b and 10a on the output side
, 10b, switching control section 1 of changeover switch 5WI-8W4
7 and a multiplexer 26, which will be described later, are connected thereto, and further an output device such as a printer or a CRT display is connected as required. Then, the control device 11 compares the detected value from the contact detection circuit 16 and a preset voltage value of a normal contact state, and when the two substantially match, it is a normal state, and when they do not match, a contact is bad. If the result of the determination is a normal state, a control signal with a logical value of "1", for example, is output to the switching control section 17, and the switching control section 17 switches the changeover switches SW, -5W4.
is switched to the measurement circuit 15 side, and a continuity test process to be described later is executed, and if the determination result is poor contact, the corresponding drive mechanisms 10a and 10b are driven again to bring the probe pins 7a and/or 7b into contact again. If the re-contact is repeated several times and still fails, it is determined that measurement is impossible, the result is stored in the storage device, and the probe pins 7a, 7b are moved to other measurement points.

The continuity test process compares the measurement value from the measurement circuit 15 with a preset reference value between the measurement points and determines whether there is a disconnection or disconnection between the measurement points.
It is determined whether there is a defective point such as a short circuit, and if a defective point exists, one of the probe pins 7a or 7b is moved along the wiring pattern la of the printed wiring board 1 to the adjacent land L. Drive mechanisms 8a, 8 to move
b, 9a, 9b and 10a, ], Ob, and calculate the resistance value R by dividing the measured value V from the voltmeter 22 of the measuring circuit 15 by the constant current value I of the constant current power supply 21. Then, the measurement point where the resistance value R is the minimum value or the maximum value is determined as a point near a short circuit, disconnection, etc., and its coordinate information is stored in the coordinate information storage area of the storage device.

As shown in FIG. 4, the measurement circuit 15 includes a constant current power source 21 connected to both ends of one contact 141 of each probe bin 7a, 7b, and a constant current power supply 21 connected to both ends of the other contact 141 of each probe bin 7a, 7b. A voltmeter 22 as a voltage detection means connected to the voltmeter 22 is provided. Then, the current value I from the constant current power supply 21.

(for example, about 0.1 A), by making the current value Iv flowing through the voltmeter 22 extremely small, for example, about 0.02 μ8 (Iv<Il), the probe bins 7a, 7b
The resistance of each contactor 14A and 14r itself and the contact resistance between the land hole and the contactor are rI+ rZ and r, respectively.
3+r4, and when the line resistance of the copper foil is Ro, the current value I of the copper foil becomes 1=II, and therefore the current value I flowing through the voltmeter 22 becomes ■,=0. Therefore, voltmeter 2
The voltage E between the terminals of 2 is Eo = E o + I v (r 3 + r 4), where Eo is the voltage applied to the copper foil.
=Eo, and each probe bin? The contact resistance and line resistance of a and 7b can be ignored, and the minute resistance value of wiring pattern 1a (about 20 mΩ when the width of the copper foil is 0.4 mm, the thickness is 20 μ, and the length is 10 mm) ) from the voltmeter 22 to the control device 11.
Output to.

The contact detection circuit 16 includes a DC power supply 25 that outputs a predetermined voltage of 12V, for example, and a positive terminal thereof and each probe bin 7a.
, 7b and the contact 14r, the contact resistance r, -
'-' The above-mentioned resistors R+ and Rz, which have extremely large resistance values compared to r4 and line resistance R0, and the negative electrode side of the DC power supply 25 and the contactor 141 of each probe bin 7a, 7b An analog multiplexer 26 which has resistors R3, R, having the same resistance value as the resistor R1°R2, and whose voltages Va and Vb between the terminals of the resistors R3 and R4 are controlled by the control device 11.
and is supplied to the input side of the control device 11 via the A/D converter 27.

Next, the operation of the above embodiment will be explained with reference to FIG. 6 showing the processing procedure of the control device 11.

Now, a land L as shown in FIG. 5 is placed on the printed wiring board 1.
A copper foil wiring pattern 1a1. between A-wLt and between lands L and -L1, respectively. lat is formed so that it is in a non-conductive state during normal operation, and as a result of testing with a multi-bin continuity tester, for example, it is assumed that a short-circuit condition is discovered between the land LA and the wiring pattern 1a+.
, laz each land LA-LE and L
It is assumed that the position coordinates of F to L1 and the fact that lands LA and LF are in a non-short circuit state are stored in advance in the storage device of the control device 11, respectively. Here, each land LA, -L, and -L to the storage device.

The position coordinates can be stored by storing the data of the CAD system used when creating the printed wiring board 1, or by reading the hole position of the land on the printed wiring board 1 with a hole position reading device and storing it. You can also do this.

First, by inputting an inspection command from the outside to the control device 11, the contact state determination process shown in FIG. 6 is executed by the control device 11.

That is, in step (2), a control signal with a logical value of "0" is output to the switch control section 14a to switch the changeover switches SW1 to S.
Switch W4 to the contact detection circuit 16 side, then step ■
Moving to the moving mechanism 2a.

A movement command is output to probe bin 7a,
With 7b raised, these are moved to lands, such as LA and L, which are the measurement starting points. Next, the process moves to step (2), where the drive mechanism IO is driven to lower the probe bins 7a and 7b and insert them into the holes provided in the lands LA and LF, and the contacts 14m! , 14r
is brought into contact with the copper foil at the land LA+LF position.

Next, the process proceeds to step (2), where the multiplexer 26 selects and reads the inter-terminal voltage Va, and then the process proceeds to step (2), where the inter-terminal voltage Va and the contact 141.14 are selected.
Resistors R3 and R when r is in normal contact with land L
If the voltage between the terminals of , that is, the voltage of the DC power supply 25 is E, then %
It is determined whether or not it is equal to a predetermined set value ■s represented by E. When the determination result is Va=Vs, it is determined that each of the contacts 14L to 14r of the probe bin 7a is in normal contact with the land L, and the process moves to step a to clear the discrepancy counter described later. Shift to step ■. Since the continuity test here is to search for short-circuited parts of the wiring pattern where the non-conducting state is normal, the equivalent circuit of the contact detection circuit 16 is as shown in FIG.
5, a parallel circuit of resistors RI and R2, resistors R, and R4
This means that the parallel circuits are connected in series,
When the contacts 141 and 14r of each probe bin 7a and 7b are in normal contact with the land L, the contact resistance r,
If ~r4 and line resistance R0 are ignored, the combined resistance of the equivalent circuit (1fi Rt is are both %E.

In step (2), the multiplexer 26 is controlled to read the inter-terminal voltage vb, and then the process proceeds to step (2), in which the inter-terminal voltage vb is set to the predetermined set value Vs, as in step (2).
It is determined whether or not it is equal to Vb = Vs.
When , each contact L41 of the probe pin 7b,
It is determined that 14r is in normal contact with the land L, and the process proceeds to step (2).

In this step (2), a control signal with a logical value of "1" is output to the switch changeover control section 14a, and the changeover switches SW, -
SW is switched to the measuring circuit 15 side, and then the process moves to step (2) to execute continuity measurement processing.

On the other hand, in the equivalent circuit of FIG. 7, each probe bin 7a
In a state where both or one of the contacts 14j2 and 7b have poor contact and the current from the DC power supply 25 is cut off, Va=vb=o, and the probe bin? When the contact 14r of a (or 7b) has a poor contact, the resistor R1 (or Rz) is not inserted, Va = Vb = E/3, and the probe bin? When the contact 141 of a (or 7b) has a poor contact, the resistor R3 (or R4) is not inserted and Va-0, Vb = 2E/3 (or Va =
2E/3. Vb = O), and the determination result of step ≠Vs becomes Va≠Vs and vb≠Vs, proceed to step 0, increment the mismatch number counter by 1'', then proceed to step 0, It is determined whether the count value C of the mismatch number counter has reached a predetermined value N (for example, 3). When the determination result is Cf=N, the process moves to step @ and the drive mechanism 10a is set in an inactive state. Then, the process returns to step (2), and when C=N, the process proceeds to step 0, where it is stored in the storage device that there is a poor contact or no conductive part is formed in the hole of the land, and step @a After clearing the discrepancy counter, return to step (2) and move the probe pin 7a and/or 7b to the next measurement point.

Similarly, when the determination result of step ■ is vb≠Vs, step ``■'' corresponding to the above steps @1 to 0
-O, and after step [phase], the process moves to step [phase] of restarting the drive mechanism lOb, and then returns to step (2). Here, the processes of steps (1) to (2) and [phase] to [phase] correspond to the contact state determination means.

In this way, when the contact state between each of the probe bins 7a and 7b and the land L is good, that is, when a=Vs and Vb=Vs, the process moves to the continuity measurement process of step (2).

In addition, if the continuity test is a test in which the land that is in a normal continuity state becomes a non-continuity state, the equivalent circuit is the 8th
As shown in the figure, a series circuit of resistors R1 and R3 and a resistor R
2 and the series circuit of the resistor R1 are inserted in the DC power supply 25 in a parallel relationship, so when the contacts 141 and 14r of each probe bin 7a and 7b are in normal contact with the land, Similarly to the above short circuit state, each resistor R3
The voltages Va and vb between the terminals of R4 and R4 are both 'AE', and the process moves to step (2) through steps (2) to (2) to execute the continuity measurement process. children 141 and 14r
If either one of them is in a poor contact state, the series circuit of resistors connected to it becomes non-conductive, so Va
=O, Vb ='AE or Va =V2E, Vb =O
STELLA 7') From @ to step [phase] to step @ to perform poor contact processing, or from step ① to step ① to step [phase] to perform poor contact processing.

Although not shown in the continuity measurement process, first the constant current 11 is supplied from the constant current power supply 21 of the measuring circuit 15 to the probe bins 7a and 7b.
Contact 14I! It is supplied to the wiring pattern 1a+1az through the wiring pattern 1a+1az. At this time, although the wiring pattern 1al+1az is in a non-conducting state and the resistance value should be infinite, it is in a short-circuited state, so the voltage value VAF according to the length of the wiring pattern including the short-circuit position is It is detected by the voltmeter 22 of the measurement circuit 15.

Next, set a reference value at the measurement starting point, that is, a relatively large resistance value R3I close to infinity when in a non-conductive state, and a relatively small resistance value R1+2 corresponding to the length of the wiring pattern when in a conductive state. Seven so]・Do. At this time, if the wiring pattern 1''++1az to be measured is supposed to be in a non-conductive state, the resistance value R is set as the reference value.
5I is set.

Next, the measured voltage VAF of the voltmeter 22 of the measuring circuit 15 is read, and this measured voltage Vat is divided by the constant current value 11 from the constant current power supply 21 set in advance to determine the lands L^ and Lr.
The resistance value R (""RAF) of the wiring pattern between the two is calculated.

Next, it is determined whether to search for a short-circuit point or a disconnection point depending on whether the resistance value R31 is set as the reference value, and since the resistance value R1l+ is set as the reference value, the short-circuit point is searched for. judge it as something.

Next, the calculated resistance value R (“RAF)” is the reference resistance value R.
It is determined whether it is greater than or equal to s+. Is this judgment a probe bin? This is to determine whether or not the land LA and LP where a and 7b are in contact are normal.In this case, the land La and Lr are short-circuited, so the resistance value RAF
becomes less than the reference resistance value R31, this resistance value RAF is stored as the minimum value Rmin in the minimum value storage area, and the coordinate position of the land LA at that time is stored in the first coordinate position storage area formed in the storage device. and then selector switch S
With W and ~SW4 in the neutral state, the measurement head 3 a +
Measurement heads 3a and 3 are moved as necessary prior to movement of measurement head 3b.
After checking whether b is a collision or not, the process returns to step (2). As a result, the probe bin 7a is moved to the next adjacent land L8 with respect to the moving mechanism 2a, and step
~ After performing contact failure detection processing for [phase], conduction measurement processing is performed again, the measured voltage ■ of the voltmeter 22 is read, and the resistance value R is calculated based on this. After that, the same operation as above is repeated. In the measurement circuit 15, the probe bins 7a, 7
The voltage value between the land and the land that b is in contact with VII
F is measured and read into the control device 1 to calculate the resistance value R8F.

At this time, in the example of Fig. 5, land L A and the vicinity of the wrinkle are short-circuited, so the current measured resistance value RBF is the resistance value between land LA and L6 compared to the previous measured resistance value RAF. Since the value becomes smaller by the amount of subtraction, the currently measured resistance value PIF is updated and stored in the 'minimum value storage area as the minimum value Rmin+, and the coordinate information of land LB is updated and stored in the coordinate position storage area.

In this way, the probe bin 7a is sequentially moved to the land Lc''.
``While moving to Lt, measure the resistance value and search for the land where the resistance value is the minimum.

In this case, as shown in FIG.
Land LD-side position P between lands Ln and Lr of 1a2
, and the land L0 position P2 between t and H-Lr, a short circuit Ps occurs between the land LD and the land 2.
The resistance value R□ between them becomes the minimum value R51n, which is updated and stored in the minimum value storage area, and the coordinate information of the land LD is updated and stored in the first coordinate information storage area.

In this state, when the resistance value REF of the next land L is calculated, this resistance value REF is larger than the previous resistance value RDF, so the probe bin 7a is moved to the coordinate position storage area with respect to the moving mechanism 2a. A movement command is output to return the coordinate information stored in the land LD position, and when the probe bin 7a comes into contact with the land LD, the other probe bin 7b is moved to the next adjacent land L. A command is output to the moving mechanism 2b, and when the movement is completed, the land L from the measuring circuit 15 is output. and Land LG
Read the measured value ■l1lG and calculate the resistance value RDG,
Next, the minimum value Rmi stored in the minimum value storage area
It is determined whether or not it is less than n (=R□). At this time, since the resistance value RUG is less than R8F, the resistance value RD
G is updated and stored in the minimum value storage area as the minimum value Rmin, and the coordinate information of lands t and e at that time is stored in a second coordinate information storage area formed in the storage device. Then, by repeating the above process, the land LH indicating the minimum resistance value for the probe bin 7b is searched, and the resistance value RD)1 is stored in the minimum value storage area, and the land LH is stored in the minimum value storage area.
When the coordinate information of land L is stored in the second coordinate information storage area and the resistance value RDI is calculated for land L,
The resistance value RDI at this time is the previous minimum value Rmin (=
Since the value is larger than Rゎ-, the inspection is continued after storing the coordinate information stored in the first and second coordinate information storage areas in respective defective location coordinate information storage areas formed in the storage device. If it is determined whether or not the test is continued, the reference value R3I is reset and the first to fourth
After clearing the coordinate information storage area and the minimum value storage area, return to step (3), and when finishing the inspection, clear the coordinate information stored in the defective location coordinate information storage area, that is, if it is on the upper side, land t, DI By reading the coordinate information of Lll and outputting it to an output device such as a printer or a CRT display, it is possible to specify the defective location where the short circuit is occurring.

In addition, although the land LE and the land 3 of the wiring pattern 1alla2 on the printed wiring board 1 to be inspected must be electrically connected by the pattern P, the land LA , LF are in a non-conductive state, the reference resistance value R32 is set, so it is determined whether the calculated resistance value R (=RAy) is less than or equal to the reference resistance value R32. This judgment is
This is to determine whether or not the land LA and LP are in a normal state. In this state, there is a disconnection between the lands LA and LF, so the resistance value RAF becomes infinite and is lower than the reference resistance value R1. Since the probe bins 7a and 7 are large,
While fixing either one of b, for example 7a, move the probe bottle 7b to land L! After moving to +, measuring circuit 15
The resistance value R is calculated by reading the measured value ■, and then it is determined whether the resistance value R exceeds the reference value R32.
3, the coordinate information of the land Lm at that time is stored in a third coordinate information storage area formed in the storage device.

Next, the probe bin 7b is moved to the next adjacent land LC, and the same process as above is repeated.

Then, while the probe bottle 7a is fixed to the land LA, the probe bottle 7b is sequentially moved to the land L.

The land is moved L, , L, , L, and the resistance values between these lands and land LA are sequentially measured. In this case, up to land LM, probe bin 7b is connected to land LA.
The resistance value of the wiring pattern la+ increases each time the wiring pattern la+ is removed, but the resistance values RAC to RAE never become larger than the reference value Ro11, and the coordinates of the land Lc''=Lt are sequentially stored in the third coordinate information storage area. The information is updated.After that, when the probe bin 7b moves from land L to land L+, the resistance value R□ becomes infinite because there is a disconnection in the center P of pattern P, and the resistance value R□ becomes infinite. Land Ll
storing the coordinate information in a fourth coordinate information storage area formed in the storage device, storing the coordinate information stored in the third and fourth coordinate information storage areas in the defective coordinate information storage area, respectively, and then Determine whether or not to end the inspection.

When one defective point is found on the relevant measurement net, the measurement is finished, and after the net has been repaired, the continuity test is performed again to confirm, so that the defective product can be repaired without any effort. It can be performed.

In the above embodiment, the case where the contact detection circuit 16 has one DC power supply 25 has been described, but the ninth embodiment
As shown in the figure, DC power supplies 25a and 25b may be individually provided for each probe bin 7a and 7b to detect the contact state of the contacts 141 and 14r. By connecting a current source to 14r and 14r and detecting the current value, the conduction state between the two may be determined, and the presence or absence of a contact failure may be determined.

Further, in the above embodiment, a case has been described in which the probe bins 7a and 7b are brought into contact again when a contact failure is detected, but the invention is not limited to this, and when a contact failure is detected, 1. It is also possible to issue an alarm.

Furthermore, although the case where the continuity test is performed using the 4-terminal method has been described, the present invention is not limited to this. Even when performing the test using the normal 2-terminal method, each probe bin 7a and the probe bin 7a, It is possible to detect the contact status of

Furthermore, it goes without saying that the present invention can be applied not only to continuity testing but also to measuring the resistance value of a wiring pattern using a probe.

Furthermore, in the above embodiment, a case has been described in which a continuity test is performed in advance using a multi-bin type HLi11 test device, and the continuity test device according to the present invention is applied when a defective net is found as a result. However, the present invention is not limited to this. Instead, the continuity testing device according to the present invention is used from the beginning to measure the resistance value between predetermined lands,
The measured resistance value is the preset reference value R@ l r
RM! The probe bins 7a and 7b are compared to determine whether they are normal or not, and when they are in a defective state, one of the probe bins 7a and 7b is sequentially moved to an adjacent land, the resistance value between the lands is measured, and the defective location is determined. Of course, the coordinate information of the land adjacent to the land may be stored in the defective location storage area of the storage device.

Furthermore, in the above embodiment, the drive mechanism 9a.

Although the case in which a ball screw is applied as 9b has been described, the present invention is not limited to this, and a timing belt or wire stretched between the rotation drive unit and the pulleys attached to the measurement heads 3a and 3b may be used. .

Furthermore, in the above embodiment, the probe bin 7a
, 7b are configured as shown in FIG. 2, but the present invention is not limited to this, and as shown in FIG. Contacts 141.14r that are insulated from each other may be formed by plating the metal 31 and removing the plating layer at symmetrical positions passing through the central axis to form the insulating parts 32. The contacts 141.14r may be held on the inner circumferential surface of an annular insulating material with a predetermined gap between them. By selecting relatively long lengths of both contacts and utilizing their elasticity, it is possible to perform four-pass inspections or resistance measurements by bringing them into contact with a flat wiring bag other than a land with a predetermined pressure. .

Further, in this embodiment, a case has been described in which two heads 3a and 3b are arranged on the upper surface side of the printed wiring board 1, but one head may be provided on the upper and lower sides with the board sandwiched therebetween.

〔Effect of the invention〕

As explained above, according to the present invention, the first and second
In the continuity testing device, each measuring element has two measuring elements that are close to each other and bordered by a a contact detection means having a contact element and detecting a contact state between each contact element of each of the measuring elements, and each of the contact elements making contact with a pattern to be inspected according to a detection result of the contact detection means. Since the structure is equipped with a contact state determination means for determining whether or not the probe is in contact with the test pattern, the regular conduction II1 test or resistance value measurement can be performed after confirming that each probe has contacted the pattern to be tested in a normal state. It is possible to reliably prevent erroneous detections in continuity tests or resistance value measurements due to poor contact between each contact on each measuring head, significantly improving the test accuracy of the testing device and improving accuracy. This has the effect of being able to do this.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing an example of a probe applicable to this invention, and FIG. 3 is an example of a control device applicable to this invention. FIG. 4 is a circuit diagram showing an example of a measurement circuit applicable to the present invention, FIG. 5 is a plan view showing an example of a wiring pattern of a printed wiring board, and FIG. 6 is a block diagram showing an example of a wiring pattern applicable to the present invention. A flowchart showing an example of the processing procedure of the control device, FIGS. 7 and 8 are circuit diagrams showing equivalent circuits of the contact detection circuit when the wiring pattern is in a conductive state and a non-conductive state, respectively,
FIG. 9 is a circuit diagram showing another embodiment of the contact detection circuit 16;
FIG. 10 is a cross-sectional view showing another embodiment of the measuring element applicable to the present invention. In the figure, 1 is a printed wiring board, 1a+, la2 are wiring patterns, 2a, 2b are moving mechanisms, 3a, 3b are measuring heads, 7a, 7b are probe bins (measuring stylus), 11 is a control device, 141, 14r are 15 is a measurement circuit, 16 is a contact detection circuit, 25 is a DC power supply, 26 is an analog multiplexer, 27 is an A/D converter, and L to L1 are lands. Fig. 1 Fig. 2 Fig. 4 RO Fig. 5 1 Print white C + thread palm book Fig. 6 Fig. 7 5 Fig. 8 3゜

Claims (1)

[Claims] In a continuity testing device that has a first and second measuring element and measures continuity or resistance between both measuring elements by bringing each measuring element into contact with a pattern to be inspected, the respective measuring elements are close to each other and insulated. contact detection means for detecting the contact state between the respective contactors of the respective measurement probes; 1. A continuity testing device comprising: contact state determining means for determining whether or not a pattern is in contact.