JP4477211B2 - Circuit board inspection equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit board inspection apparatus configured to be able to perform a predetermined electrical inspection in a state in which an inspection probe is in contact with a conductor pattern formed on a circuit board to be inspected. The present invention relates to a circuit board inspection apparatus suitable for inspecting a circuit board in which each end is commonly connected to a connection conductor.
[0002]
[Prior art]
As this type of circuit board inspection apparatus, a circuit board inspection apparatus 31 shown in FIG. 6 is conventionally known. The circuit board inspection device 31 follows the guidance of a probe moving mechanism (not shown), and probes 3a and 3b that come into contact with the conductor pattern formed on the circuit board P to be inspected, and inspection signals via the probes 3a and 3b. A power supply unit PW for output, an ammeter AM, and a control unit (not shown) that performs a conductor pattern disconnection inspection and an insulation inspection between the conductor patterns based on a current value detected by the ammeter AM. On the other hand, the circuit board P is a package board on which a bare chip integrated circuit (hereinafter referred to as “IC”) can be mounted as an example, and is formed in a flat plate shape as a whole. Further, as shown in FIG. 4, the circuit board P has bonding pads 22a, 22b, 22, 22... (Hereinafter referred to as “bonding pads 22” when not distinguished from each other) for connecting IC connection terminals by bonding or soldering. Are provided with conductor patterns 23a, 23b, 23, 23... (Hereinafter referred to as “conductor patterns 23” when not distinguished), and each conductor pattern 23 is arranged at a very fine pitch. It is connected to the plating ring 24 in a state of being arranged in a shape. Therefore, in this state, the bonding pads 22, 22... Are connected to each other through the conductor patterns 23, 23.
[0003]
When the circuit board inspection is performed by the circuit board inspection apparatus 31, first, as shown in FIG. 7, for example, the probes 3a and 3b are brought into contact with the bonding pads 22a and 22b, respectively. Next, the control unit controls the power supply unit PW to output a test signal, and the resistance value between the bonding pads 22a and 22b is determined based on the voltage value and the current value detected by the ammeter AM. calculate. In this case, as shown in the equivalent circuit diagram of FIG. 6, the conductor patterns 23a and 23b and the plating ring 24 are represented by extremely small resistances. Therefore, the calculated resistance value is a combined resistance value of the conductor pattern 23a (resistance R1), the conductor pattern 23b (resistance R2), and the plating ring 24 (resistance R11). Next, the calculated resistance value is compared with the upper and lower limit values defined based on the resistance value previously absorbed from the non-defective circuit board. In this case, when the calculated resistance value is within the range of the upper and lower limit values, it is determined that there is no short-circuit portion between the bonding pads 22a and 22b. On the other hand, when the calculated resistance value exceeds the upper limit value, it is determined that a broken portion exists in any of the conductor patterns 23a and 23b and the plating ring 24. Further, when the calculated resistance value falls below the lower limit value, it is determined that a short-circuit portion exists between the conductor patterns 23a and 23b. The circuit board P is inspected by performing the above inspection on all the adjacent bonding pads 22 and 22.
[0004]
[Problems to be solved by the invention]
However, the conventional circuit board inspection apparatus 31 has the following problems. That is, in the conventional circuit board inspection apparatus 31, when the circuit board P is inspected, the disconnection / short circuit inspection is performed in a state where the probes 3 a and 3 b are in contact with the adjacent bonding pads 22 and 22. In this case, when the probes 3a and 3b come into contact with each other, a resistance value lower than the lower limit value is calculated. Therefore, it is erroneously determined that there is a short-circuited portion between the conductor patterns 23a and 23b. On the other hand, the bonding pads 22 and 22 are formed at a very fine pitch. For this reason, there is a problem that it is very difficult to reliably contact the adjacent bonding pads 22 and 22 without bringing the probes 3a and 3b into contact with each other.
[0005]
Further, since probing is difficult in the conventional circuit board inspection apparatus 31, the probe 3a is shifted from the position to be originally contacted and brought into contact with a position near the plating ring 24 as shown by a broken line in FIG. Sometimes. In such a case, since the pattern length between the probes 3a and 3b is shorter than that in the normal contact state, a resistance value that is lower than the lower limit value is calculated. There is a problem.
[0006]
The present invention has been made in view of such problems, and it is a main object of the present invention to provide a circuit board inspection apparatus that can be easily probed and can improve inspection accuracy.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a circuit board inspection apparatus according to claim 1 is provided with a power supply unit for generating an inspection signal and first to third inspection elements that can contact a conductor pattern formed on a circuit board to be inspected. A probe, a current detection means, and a switch; one end of the switch is connected to one output part of the power supply; and the current detection means is connected between the one end of the switch and the first inspection probe; A second inspection probe is connected to the other end of the power supply section, and a third inspection probe is connected to the other output section of the power supply section. When inspecting a circuit board whose part is commonly connected to the connection conductor, the first inspection probe is brought into contact with the other end of the one conductor pattern, and the second conductor pattern is connected to the connection portion of the one conductor pattern. Inspection probe The third inspection probe is brought into contact with a predetermined position on the connection conductor separated from the connection site, and the second inspection probe and one output portion of the power supply section are separated by a switch. One conductor when a current exceeding a predetermined threshold is detected by the current detecting means in a state where the current is detected by the detecting means and the second inspection probe and one output unit are connected by the switch. It is determined that the pattern is short-circuited to another conductor pattern. In the state in which the second inspection probe and one output part of the power supply unit are connected by a switch, current does not flow when there is no short-circuited part, whereas current is reliably supplied when there is a short-circuited part. Since it flows, the “predetermined threshold value” can be defined as 0A. That is, it may be determined that a short-circuited portion exists when the current detection unit can detect that a current has flowed.
[0008]
The circuit board inspection apparatus according to claim 2 is the circuit board inspection apparatus according to claim 1, wherein the current detection means detects the current in a state in which the second inspection probe and one output unit are separated by a switch. In this case, it is determined that there is no disconnection between the one conductor pattern and the connecting conductor. It may be determined that there is no disconnection when a current exceeding a predetermined threshold is detected by the current detection means.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of a circuit board inspection apparatus according to the present invention will be described below with reference to the accompanying drawings.
[0010]
First, the configuration of the circuit board inspection apparatus 1 will be described with reference to the drawings. In addition, about the circuit board P to be inspected, the same reference numerals are given, and redundant description is omitted.
[0011]
As shown in FIG. 1, the circuit board inspection apparatus 1 includes probe moving mechanisms (hereinafter referred to as “moving mechanisms”) 2, 2, 2, contact type probes 3 a to 3 c, a substrate inspection unit 4, a control unit 5, and a RAM 6. And a ROM 7. In this case, the probes 3a to 3c correspond to first to third inspection probes in the present invention, and are attached to the moving mechanisms 2, 2, and 2 via probe fixtures (not shown), respectively. The board inspection unit 4 includes, for example, a power supply unit PW that generates a DC voltage inspection signal, an ammeter AM corresponding to the current detection means in the present invention, and a switch SW. Configure. In this case, as shown in FIG. 2B, the fixed contact (one end) of the switch SW is connected to the negative output part (one output part) of the power supply part PW, and one end of the ammeter AM is connected to the fixed contact. The probe 3a is connected to the other end of the ammeter AM. The probe 3b is connected to the movable contact (the other end) of the switch SW, and the probe 3c is connected to the plus output part (the other output part) of the power supply part PW.
[0012]
Further, the switch SW connects or disconnects the probe 3b and the minus output unit of the power supply unit PW according to the control of the control unit 5. The control unit 5 executes pass / fail determination of the circuit board P based on the current value detected by the ammeter AM, operation control of the power supply unit PW, the switch SW, and the moving mechanisms 2, 2, and 2. The RAM 6 temporarily stores the calculation result of the control unit 5, and the ROM 7 stores the operation program of the control unit 5.
[0013]
Next, for example, an inspection process for inspecting a package substrate will be described with reference to the drawings.
[0014]
First, the control unit 5 controls the moving mechanisms 2, 2, and 2 to bring the probes 3 a to 3 c into contact with the circuit board P as shown in FIG. At this time, for example, the probe 3a is brought into contact with the bonding pad 22a, the probe 3b is brought into contact with the connection portion of the plating ring (connecting conductor) 24 with the conductor pattern 23a, and a predetermined length from the contact position of the probe 3b. The probe 3c is brought into contact with a predetermined position on the plating ring 24 separated as described above. In this case, the predetermined length is defined, for example, as a length exceeding the arrangement pitch length of the conductor patterns 23, 23,... Connected to the plating ring 24. Therefore, for example, the probe 3 c is brought into contact with the corner of the plating ring 24. In this case, in this circuit board inspection apparatus 1, since the probes 3a to 3c are brought into contact with positions separated from each other to some extent, it is necessary to bring the probes 3 and 3 into contact with the adjacent bonding pads 22a and 22b. Compared with the board inspection apparatus 31, the mutual contact can be surely avoided, so that probing becomes very easy.
[0015]
Next, after controlling the switch SW to a disconnected state, the control unit 5 drives and controls the power supply unit PW to output an inspection signal between the probes 3a and 3c, and in this state, performs a disconnection inspection of the conductor pattern 23a. To do. At this time, if no current is detected by the ammeter AM, the control unit 5 indicates that a contact failure has occurred in either the probe 3a or 3c, or there is a broken portion in either the conductor pattern 23a or the plating ring 24. Then, it is determined. At this time, the control unit 5 controls the moving mechanisms 2 and 2 to perform reprobing on the probes 3a and 3c, and performs the disconnection inspection again. Also in this case, if no current is detected by the ammeter AM, the control unit 5 determines that there is a broken portion in either the conductor pattern 23a or the plating ring 24.
[0016]
On the other hand, when the current is detected, the control unit 5 determines that the probes 3a and 3c are in normal contact with the circuit board P and that there is no disconnection in both the conductor pattern 23a and the plating ring 24. . At this time, an insulation test between the conductor patterns 23a and 23b is performed in a state where the probes 3a to 3c are in contact with the circuit board P. When performing an insulation test, the control unit 5 first controls the switch SW to be in a connected state to connect the probe 3b to the minus output unit of the power supply unit PW. Next, the power supply unit PW is driven and controlled to output an inspection signal. In this case, as shown in FIG. 2B, each of the conductor patterns 23a, 23b, 23,... Has resistors R1, R2, R3,. Resistances R11, R12, R13,... R1N as resistance components also exist between the connection portions with the conductor patterns 23 in FIG. Accordingly, when the conductor patterns 23a and 23b are normally insulated, the series circuit of the resistor R1 and the ammeter AM is short-circuited by the switch SW, so that the current I1 based on the inspection signal of the power supply unit PW is supplied to the probe 3c. The current flows through the path composed of the plating ring 24, the probe 3b and the switch SW, and no current flows through the path composed of the probe 3c, the plating ring 24, the conductor pattern 23a, the probe 3a and the ammeter AM. As a result, the current value detected by the ammeter AM is approximately 0A. In this case, when the current value detected by the ammeter AM falls below a predetermined threshold value (for example, 100 μA) (or when it is 0 A), the control unit 5 normally insulates between the conductor patterns 23a and 23b. It is determined that there is.
[0017]
On the other hand, when the conductor patterns 23a and 23b are short-circuited at the portion X as shown in FIGS. 5 and 3A, the resistor R1 is divided into resistors R1a and R1b as shown in FIG. 3B. The resistor R2 is divided into resistors R2a and R2b, and an equivalent circuit in which both the dividing points (part X) are connected by the resistor Rx is represented. Accordingly, since both ends of the ammeter AM are not short-circuited by the switch SW, even when the switch SW is connected, the current I11 flows through the path including the probe 3c, the plating ring 24, the probe 3b, and the switch SW, and the probe SW The current I12 flows through a path formed by 3c, the plating ring 24, the resistor R2b, the resistor Rx, the resistor R1a, the probe 3a, and the ammeter AM. As a result, unlike the non-defective circuit board P, the ammeter AM detects a current value exceeding a predetermined threshold value. Therefore, the control unit 5 determines that a short circuit has occurred between the conductor patterns 23a and 23b. On the other hand, as shown in FIG. 5 and FIG. 3 (a), the conductor patterns 23a and 23b are short-circuited at the short-circuit portion X, and the conductor pattern 23a is formed between the short-circuit portion X and the plating ring 24. There may be a disconnection at the part Y between. In this case, although the circuit board P is determined to be non-defective during the disconnection inspection described above, a current value exceeding a predetermined threshold value is detected by the ammeter AM during the insulation inspection. Can be reliably determined.
[0018]
Thereafter, in the disconnection insulation inspection with respect to the conductor pattern 23b, the probe 3a is brought into contact with the bonding pad 22b and the probe 3b is brought into contact with the connection portion of the plating ring 24 with the conductor pattern 23b. The electrical inspection is performed in the same manner as the disconnection inspection and the insulation inspection. The quality of the circuit board P is determined by performing the disconnection inspection and the insulation inspection for every conductor pattern 23, 23,.
[0019]
The present invention is not limited to the above-described embodiments. For example, the circuit board inspection apparatus 1 is configured to be able to perform an electrical inspection using three probes 3a to 3c, but the number of inspection probes in the present invention is not limited to this, and more By providing the probes and selecting three probes from these probes and connecting them to the substrate inspection unit 4, the inspection time can be shortened. Further, the inspection signal is not limited to the DC voltage, and an AC voltage can also be used. Furthermore, the current detection means is not limited to an ammeter, and may be configured using a current transformer.
[0020]
【The invention's effect】
As described above, according to the circuit board inspection apparatus of the present invention, the electrical inspection is performed by bringing the first to third inspection probes into contact with the positions separated from each other on the circuit board. Even when the conductor pattern is formed at a fine pitch, probing is facilitated. Further, by performing a disconnection inspection between the first inspection probe and the third inspection probe prior to the insulation inspection between the conductor patterns, a misjudgment caused by a contact failure of the inspection probe during the insulation inspection. Differentiation can be avoided, thereby improving the inspection accuracy. Even when each inspection probe is misaligned and probing, it is short-circuited to the conductor pattern to be inspected when the second inspection probe and one output part of the power supply part are connected by a switch. When there is a location, the current detection means reliably detects the current, and when there is no short-circuit location, no current is detected, so the presence or absence of the short-circuit location can be reliably inspected. Accuracy can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a circuit board inspection apparatus 1 according to an embodiment of the present invention.
2A is a plan view of a state in which the probes 3a to 3c are in contact with the circuit board P, and FIG. 2B is a circuit board inspection apparatus in which the conductor patterns 23a and 23b are normally insulated. 1 and an equivalent circuit diagram of a circuit board P. FIG.
3A is a plan view of a state in which the probes 3a to 3c are in contact with the circuit board P, and FIG. 3B is a circuit board in a state in which a short-circuit portion is present in a portion X between the conductor patterns 23a and 23b. 3 is an equivalent circuit diagram of the inspection apparatus 1 and the circuit board P. FIG.
4 is a plan view of a circuit board P, which is an example of an inspection target of the circuit board inspection apparatus 1 according to the embodiment of the present invention and the conventional circuit board inspection apparatus 31. FIG.
5 is a plan view of the vicinity of conductor patterns 23a and 23b on a circuit board P. FIG.
6 is an equivalent circuit diagram of a conventional circuit board inspection apparatus 31 and circuit board P. FIG.
7 is a plan view showing a state in which probes 3a and 3b are in contact with a circuit board P. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Circuit board inspection apparatus 3a-3c Probe 4 Board inspection part 22,22a, 22b Bonding pad 23,23a, 23b Conductor pattern 24 Ring for plating AM Ammeter P Circuit board PW Power supply part SW Switch

Claims (2)

A power supply unit that generates a signal for inspection; first to third inspection probes that can contact a conductor pattern formed on a circuit board to be inspected; a current detection unit; and a switch; One end of the switch is connected to one output section of the switch, the current detection means is connected between one end of the switch and the first inspection probe, and the second inspection is connected to the other end of the switch. A board inspection apparatus configured to connect a probe and connect the third inspection probe to the other output section of the power supply section,
When inspecting a circuit board in which each one end portion of the plurality of conductor patterns is commonly connected to the connection conductor, the first inspection probe is brought into contact with the other end portion of the one conductor pattern, and the connection conductor The second inspection probe is brought into contact with the connection portion of the one conductor pattern in the first contact pattern, the third inspection probe is brought into contact with a predetermined position on the connection conductor spaced apart from the connection portion, and the second Current is detected by the current detection means in a state where the inspection probe and the one output part of the power supply part are separated by the switch, and the second inspection probe and the one output part are When a current exceeding a predetermined threshold is detected by the current detection means in a state of being connected by a switch, the one conductor pattern is changed to another conductor pattern. Circuit board inspection apparatus characterized by determining to be circuited. When a current is detected by the current detection means in a state where the second inspection probe and the one output portion are separated by the switch, a disconnection occurs between the one conductor pattern and the connection conductor. The circuit board inspection apparatus according to claim 1, wherein it is determined that the circuit board does not exist.

Images