JP4411064B2 - Bypass capacitor mounting / non-mounting inspection method - Google Patents

Description

The present invention relates to mounting and non-mounting inspection how the bypass capacitor for inspecting the presence or absence of the bypass capacitor is mounted between the power supply pattern and the ground pattern of the circuit board.

  In a circuit board inspection apparatus such as an in-circuit tester, when performing a circuit element mounting inspection, for example, with reference to the standard value of the circuit element, it is determined whether the obtained measurement value is within the standard value. Like to do.

  As an example, when inspecting whether or not a 1 kΩ resistive element is mounted, the resistance value between both ends of the resistive element is measured, and if the measured value is within the range of 1 kΩ ± α (allowable value) For example, when 100 kΩ is measured, it is determined that the mounting is wrong.

  This determination method may not be applicable to bypass capacitors. That is, the bypass capacitor is connected in parallel with the load resistance when, for example, it is desired to flow only the direct current through the load resistance in the circuit in which the direct current and the alternating current flow. It does not require very high accuracy, and its capacitance value varies.

  In many cases, a plurality of bypass capacitors are connected in parallel between a power supply pattern of a circuit board and a GND (ground) pattern. For example, five capacitors (a) 120 nF, (b) 150 nF, (c) 150 nF, (d) 100 nF, and (e) 80 nF are connected in parallel between the power supply pattern and the GND pattern. Suppose that

  When the capacitance C between the power supply pattern and the GND pattern of the five capacitor groups is measured, C = 600 nF is obtained because of the parallel connection. If (d) a 100 nF capacitor is not mounted and not actually mounted, C = 500 nF. Therefore, when detecting the presence / absence of a capacitor with a non-defective product determination reference value of, for example, 500 nF ± 30%, (d) OK (PASS) determination is made even if a 100 nF capacitor is not mounted.

  Therefore, image processing is employed for checking the presence or absence of a large number of bypass capacitors connected in parallel as described above (for example, see Patent Document 1 below).

JP-A-6-243235

  However, since image processing requires expensive equipment, the cost burden is large. Further, since the comparison inspection is based on the image pattern, erroneous detection is likely to occur particularly in a small chip. Furthermore, there is a problem that even if it is not electrically connected, if there is a part there, it is judged as a non-defective product.

Thus, issues of the present invention, without using image processing is to be able to inspect the presence or absence of easily and reliably bypass capacitors less expensive equipment.

To solve the above Symbol challenges, the invention includes the presence of the bypass capacitor is mounted between the solder pads included in the solder pads and the ground pattern that is included in the power supply pattern formed on the circuit board according to claim 1 In a bypass capacitor mounting / non-mounting inspection method for inspecting a signal, a first probe connected to the signal generation source and its output terminal, and a second probe connected to each voltage input terminal of the voltage detection means and the voltage detection means , A third probe, the third probe as a guard probe, the first probe in contact with a solder pad to which one electrode terminal of the bypass capacitor is connected, and the second probe connected to the other of the bypass capacitor together brought into contact with the solder pad electrode terminals of the are connected, the said third probe second probe A predetermined measurement signal is generated from the signal generation source in a state where it is in contact with either the power supply pattern or the ground pattern on the solder pad side that is in contact, and the voltage detection means performs the first measurement. A voltage between two probes and the third probe is detected to check for the presence of the bypass capacitor.

  According to a second aspect of the present invention, there is provided a bypass capacitor in which a plurality of solder capacitors are mounted in parallel between a solder pad included in a power supply pattern formed on a circuit board and a solder pad included in a ground pattern. In a mounting / non-mounting inspection method of a bypass capacitor for inspecting presence / absence, a first probe connected to a signal generation source and its output terminal, and a second connected to each voltage input terminal of the voltage detection means and the voltage detection means. A probe and a third probe, and the third probe is used as a guard probe, and the second probe is brought into contact with a solder pad to which one electrode terminal of one specific bypass capacitor arbitrarily selected as an inspection object is connected. The power supply pattern on the solder pad side where the second probe is in contact with the third probe The signal is generated in a state where the first probe is brought into contact with any one of the ground patterns and the first probe is brought into contact with a predetermined portion having the same potential as the solder pad to which the other electrode terminal of the specific bypass capacitor is connected. A predetermined measurement signal is generated from a source, and the voltage detection means detects the voltage between the second probe and the third probe to check the presence or absence of the bypass capacitor. Can also solve the first problem.

  In the invention according to claim 2, as described in claim 3, the predetermined location for contacting the first probe is a solder pad side to which the other electrode terminal of the specific bypass capacitor is connected. It is preferable that any one of the power supply pattern and the ground pattern, or another bypass capacitor connecting solder pad included in the other pattern.

  According to a fourth aspect of the present invention, there is provided a bypass capacitor in which a plurality of solder pads are mounted in parallel between a solder pad included in a power supply pattern formed on a circuit board and a solder pad included in a ground pattern. In a mounting / non-mounting inspection method of a bypass capacitor for inspecting presence / absence, a first probe connected to a signal generation source and its output terminal, and a second connected to each voltage input terminal of the voltage detection means and the voltage detection means. A probe and a third probe, and the third probe is used as a guard probe, and the second probe is brought into contact with a solder pad to which one electrode terminal of one specific bypass capacitor arbitrarily selected as an inspection object is connected. The power supply pattern on the solder pad side where the second probe is in contact with the third probe A predetermined measurement signal is generated from the signal source in a state where the first probe is brought into contact with one of the ground patterns and the first probe is brought into contact with a predetermined portion having the same potential as that of the third probe. And detecting the voltage between the second probe and the third probe by the voltage detecting means to check the presence or absence of the bypass capacitor, thereby also solving the first problem can do.

  In the invention according to claim 4, as described in claim 5, either of the power supply pattern or the ground pattern in contact with the third probe may be used as the predetermined portion that contacts the first probe. It is preferable that the solder pad is for connecting one of the patterns or the other bypass capacitor included in the one pattern.

  In the first to fifth aspects of the invention, as described in the sixth aspect, the circuit board is a multilayer board, and a solder pad for soldering the bypass capacitor is formed on one surface of the circuit board. In the case where the power supply pattern and the ground pattern are formed on the other surface of the circuit board and are connected through a through hole, the third probe is connected to the circuit board in order to increase the inspection accuracy. It is preferable to contact the end surface of the through hole exposed to be electrically contactable with the other surface.

  According to the first to sixth aspects of the invention, the low cost includes the first probe connected to the signal generation source and its output terminal, and the second and third probes connected to the voltage detection means and each of its output terminals. The presence or absence of a bypass capacitor can be easily and reliably inspected with simple equipment.

Further, Voltage Detection reading V is "V = 0" means if successful, it can be determined that the abnormality if "V ≠ 0", there is no particular need to prepare a reference value for judgment. Therefore, the preparatory work before entering the inspection is unnecessary, and the inspection can be started as it is.

First, FIGS. 1 to 5, will be described engagement Ru implementation form the mounting and non-mounting inspection method of the bypass capacitor according to the present invention. FIG. 1 is a side view schematically showing a state where the bypass capacitor 20 is mounted on the circuit board 10, FIG. 2 is a plan view showing the main part thereof, and FIG. 3 is a schematic view showing an inspection example when mounted and not mounted. FIG. 4, FIG. 4 and FIG. 5 are schematic views showing other inspection examples.

  In this example, the circuit board 10 is a double-sided board, and a pair of solder pads 11 and 12 for soldering the bypass capacitor 20 are formed on one surface (the upper surface in FIG. 1). A power pattern 13 and a GND (ground) pattern 14 are formed on the other surface (the lower surface in FIG. 1).

  One solder pad 11 and the power supply pattern 13 are conducted through the through hole 15, and the other solder pad 12 and the GND pattern 14 are conducted through the through hole 16. As shown in FIG. 2, the solder pad 11 and the through hole 15 are connected by a lead line 11a, and the solder pad 12 and the through hole 16 are similarly connected by a lead line 12a.

  In this example, the bypass capacitor 20 is a chip-type capacitor, and includes a capacitor body 21 having, for example, a laminated electrode inside a resin exterior body, and a pair of electrode terminals 22 and 23 provided at both ends of the capacitor body 21. ing. In the following description, the bypass capacitor 20 may be simply referred to as a capacitor.

  In the case of a nonpolar capacitor, there is no particular mounting direction. In this example, one electrode terminal 22 of the capacitor 20 is soldered to the solder pad 11 on the power supply pattern 13 side, and the other electrode terminal 23 is connected to the GND pattern. It is mounted on the circuit board 10 so as to be soldered to the 14th solder pad 12.

  In order to inspect the presence or absence of the capacitor 20, a voltage generation unit 30 as a signal generation source and a voltmeter 40 as a voltage detection means are used. The voltage generator 30 may be either an AC voltage generator or a DC voltage generator, and the probe P1 is connected to its voltage output terminal. The other terminal of the voltage generator 30 is grounded. The signal generation source may be a current generation source.

  The probe P2 and the probe P3 are connected to the voltage input terminal of the voltmeter 40. In this case, the probe P3 is grounded as a guard probe. Each of the probes P1 to P3 may be a movable probe that can move in the X-Y direction, or may be a fixed probe that is implanted in a pin board.

  In order to inspect whether the bypass capacitor 20 is mounted between the solder pads 11 and 12, the probe P1 drawn from the voltage generator 30 is brought into contact with the solder pad 12 on the GND pattern 14 side, for example. Further, of the probes P2 and P3 drawn out from the voltmeter 40, the probe P2 is brought into contact with the solder pad 11 on the power supply pattern 13 side, and the ground side probe P3 is connected to the lower surface side (rear surface side) in FIG. ) Are brought into contact with the power supply pattern 13 wired in the circuit.

  As shown in FIG. 2, the probe P3 on the ground side may be brought into contact with the end surface of the through hole 15 exposed on the upper surface side of the circuit board 10 in FIG. Here, the reason why the probe P3 is brought into contact with the end face of the through hole 15 is because the solder resist is not formed in the through hole 15 in general.

  In addition to the through hole 15, if there is a portion that communicates with the power supply pattern 13 and can contact the probe, the probe P <b> 3 may be brought into contact therewith. In short, the probe P3 may be brought into contact with a position distant from the probe P2, but in order to increase the voltage detected between the probe P2 and the probe P3, as shown in FIG. P3 is preferably brought into contact with the power supply pattern 13 on the back side of the circuit board 10 to increase the distance between the probe P2 and the probe P3. Further, the contact location of the probe P2 is not limited to the solder pad 11 on the power supply pattern 13 side.

  After the probes P1 to P3 are brought into contact as described above, a predetermined voltage is generated from the voltage generator 30. As shown in FIG. 3A, when the bypass capacitor 20 is mounted between the solder pads 11 and 12, current flows between the probes P2 and P3 via the bypass capacitor 20, so that the voltmeter 40 The voltage drop during that time is measured. That is, if the reading of the voltmeter 40 is V, then V ≠ 0.

  On the other hand, as shown in FIG. 3B, when the bypass capacitor 20 is not mounted between the solder pads 11 and 12, no current flows between the probes P2 and P3. The reading is V = 0.

  In this way, according to the present invention, if the reading of the voltmeter 40 is V ≠ 0, it can be determined to be mounted, and if V = 0, it is determined not to be mounted. In addition, since it is only necessary to determine whether V ≠ 0 or V = 0, that is, whether it is 0 or 1, it is not necessary to prepare a reference value for the determination. Even when the voltage generator 30 is a DC voltage generator, the current flows for a moment through the bypass capacitor 20 when the voltage is applied, so that the inspection is possible.

  In the above example, the probe P1 drawn from the voltage generator 30 is brought into contact with, for example, the solder pad 12 on the GND pattern 14 side, but the contact location of the probe P1 is not limited to this. This will be described with reference to FIGS. A plurality of bypass capacitors 20 are usually connected in parallel between the power supply pattern 13 and the GND pattern 14, but three bypass capacitors 20a to 20c are connected in FIGS. 4 and 5A. Indicates.

  In the example of FIG. 4, when the bypass capacitor 20a is a specific bypass capacitor to be inspected, the probes P2 and P3 drawn from the voltmeter 40 are connected to the probe P2 as in the above example. It is preferable that the power supply pattern 13 side solder pad 11 connected to one electrode terminal 22 of 20a is brought into contact, and the ground side probe P3 is brought into contact with the end face of the through hole 15 connecting the solder pad 11 to the power supply pattern 13. .

  On the other hand, the probe P1 drawn out from the voltage generation unit 30 may be brought into contact with a portion having the same potential as the solder pad 12 connected to the other electrode terminal 23 of the specific bypass capacitor 20a. Since the solder pad 12 is electrically connected to the GND pattern 14 through the through hole 16, the contact point of the probe P1 is the end surface of the through hole 16 of the other mounting portion where the bypass capacitor 20c is mounted as in the example of FIG. It may be, or the solder pad 12 of another mounting part. In this example, as a result of the inspection, if the reading value of the voltmeter 40 is V ≠ 0, it can be determined to be mounted, and if V = 0, it is determined not to be mounted.

  As another example, as shown in FIG. 5A, the probe P1 drawn out from the voltage generator 30 may be brought into contact with the power supply pattern 13 side. As for the probes P2 and P3 drawn from the voltmeter 40, the probe P2 is connected to one electrode terminal 22 of the specific bypass capacitor 20a to be inspected on the side of the power supply pattern 13 as in the above example. The probe P3 on the ground side is brought into contact with the end surface of the through hole 15 that connects the solder pad 11 to the power supply pattern 13.

That is, the probe P1 may be brought into contact with a portion having the same potential as the probe P3 on the ground side. In this example, the probe P1 is used as the end surface of the through hole 15 of the adjacent mounting portion where the bypass capacitor 20a is mounted. However, the probe P1 may be brought into contact with the solder pad 11 connected to the through hole 15. Any mounting part other than the mounting part of the specific bypass capacitor 20a to be inspected may be selected.

  As shown in FIG. 5A, after the probes P1 to P3 are brought into contact with each other, a predetermined voltage is generated from the voltage generator 30. Thus, when both the specific bypass capacitor 20a and the adjacent bypass capacitor 20b are mounted, as shown in FIG. 5B, along with the current path A that travels from the probe P1 to the power supply pattern 13 toward the probe P3. Since the current path B from the probe P1 to the probe P3 through the bypass capacitor 20b and the specific bypass capacitor 20a is formed, the reading value of the voltmeter 40 becomes V ≠ 0, and the determination is implemented.

  On the other hand, as shown in FIG. 5C, for example, when the specific bypass capacitor 20a is not mounted, since the current path B is not formed, the reading value of the voltmeter 40 becomes V = 0 and the determination is made. Not implemented. Even when the adjacent bypass capacitor 20b is not mounted, the reading of the voltmeter 40 is V = 0.

Side view schematically showing the engagement Ru implementation form the mounting and non-mounting inspection method of the bypass capacitor according to the present invention. The top view corresponding to FIG. (A) In the above you facilities embodiment, schematic diagram showing a test example of a state in which the bypass capacitor is mounted, in the above you facilities embodiment (b), shows a test example of the state where the bypass capacitor not implemented Pattern diagram. Schematic diagram for explaining another example of the above you facilities embodiment. (A) above you facilities schematic diagram for further explaining another example embodiment, (b) schematic diagram illustrating a test example of a state in which the bypass capacitor is mounted, has been implemented (c) a bypass capacitor FIG .

10 circuit board 11 solder pad 13 power supply pattern 14 GND pattern 15 through-hole 20 bypass capacitor 21 capacitor body 22, 23 electrode terminal 30 voltage generator 40 Voltmeter

Claims (6)

In a bypass capacitor mounting / non-mounting inspection method for inspecting the presence or absence of a bypass capacitor mounted between a solder pad included in a power supply pattern formed on a circuit board and a solder pad included in a ground pattern,
A first probe connected to the signal generation source and its output terminal, a voltage detection means, and a second probe and a third probe connected to each voltage input terminal of the voltage detection means, and guarding the third probe As a probe, the first probe is brought into contact with a solder pad to which one electrode terminal of the bypass capacitor is connected, and the second probe is brought into contact with a solder pad to which the other electrode terminal of the bypass capacitor is connected , A predetermined measurement signal is generated from the signal generation source in a state in which the third probe is in contact with either the power supply pattern or the ground pattern on the solder pad side with which the second probe is in contact. The voltage detection means detects the voltage between the second probe and the third probe, and Mounting and non-mounting inspection method of the bypass capacitor, which comprises examining the presence or absence of bypass capacitors. Mounting / non-passing of bypass capacitors to inspect for the presence or absence of bypass capacitors that are mounted in parallel between the solder pads included in the power supply pattern formed on the circuit board and the solder pads included in the ground pattern In the mounting inspection method,
A first probe connected to the signal generation source and its output terminal, a voltage detection means, and a second probe and a third probe connected to each voltage input terminal of the voltage detection means, and guarding the third probe As the probe, the second probe is brought into contact with a solder pad to which one electrode terminal of one specific bypass capacitor arbitrarily selected as an inspection object is connected, and the third probe is in contact with the third probe. The power supply pattern or the ground pattern on the solder pad side is brought into contact with one of the patterns, and the first probe is placed at a predetermined location having the same potential as the solder pad to which the other electrode terminal of the specific bypass capacitor is connected. In a contact state, a predetermined measurement signal is generated from the signal generation source, and the voltage detection means 2 probe and the third mounting and non-mounting inspection method of the bypass capacitor, characterized in that by detecting the voltage between the probe for inspecting the presence or absence of the bypass capacitor.   The predetermined location with which the first probe is brought into contact is included in either the power supply pattern or the ground pattern on the solder pad side to which the other electrode terminal of the specific bypass capacitor is connected, or the other pattern. The mounting / non-mounting inspection method for a bypass capacitor according to claim 2, wherein the solder pad is used for connecting the bypass capacitor. Mounting / non-passing of bypass capacitor to inspect presence / absence of multiple bypass capacitors mounted in parallel between solder pads included in power supply pattern formed on circuit board and solder pads included in ground pattern In the mounting inspection method,
A first probe connected to the signal generation source and its output terminal, a voltage detection means, and a second probe and a third probe connected to each voltage input terminal of the voltage detection means, and guarding the third probe As the probe, the second probe is brought into contact with a solder pad to which one electrode terminal of one specific bypass capacitor arbitrarily selected as an inspection object is connected, and the third probe is in contact with the third probe. The signal in the state where the power supply pattern on the solder pad side or the ground pattern is brought into contact with the first probe in contact with a predetermined location having the same potential as the contact location of the third probe. A predetermined measurement signal is generated from a generation source, and the voltage between the second probe and the third probe is detected by the voltage detection means. Detecting and mounting and non-mounting inspection method of the bypass capacitor, which comprises examining the presence or absence of the bypass capacitor.   The predetermined location for contacting the first probe is either one of the power supply pattern or the ground pattern in contact with the third probe, or another bypass capacitor connecting solder pad included in the one pattern. The mounting / non-mounting inspection method for a bypass capacitor according to claim 4.   The circuit board is a multilayer board, the solder pads are formed on one side of the circuit board, the power supply pattern and the ground pattern are formed on the other side of the circuit board, and they are connected through a through hole. 6. The bypass according to claim 1, wherein the third probe is brought into contact with an end surface of the through hole exposed to be electrically contactable with the other surface of the circuit board. Capacitor mounting / non-mounting inspection method.

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