JP2009257863A - Electronic circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic circuit board capable of reliably detecting whether solder joints between electronic components and a board are fractured. <P>SOLUTION: The electronic circuit board 1 includes a monitoring means 13 for monitoring the state of solder joints 12, which join a board body 10 and electronic components 11 to each other, between two points included in a solder joint 12 to detect fractures. Preferably, the monitoring means 13 monitors the conditions of solder joints 12 which fracture due to a prescribed thermal stress or greater one among solder joints between the board body 10 and an electronic component 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electronic circuit board, and more particularly to an electronic circuit board suitable for mounting on an electronic device installed outdoors such as a gas meter, a water meter, and a centralized monitoring device.

  An electronic circuit board is formed by joining electronic components on a substrate subjected to an insulation process such as a printed circuit board by solder bonding. By the way, electronic circuit boards mounted on products installed outdoors are exposed to open-air environments such as direct sunlight, rain, and snow, so that thermal stress due to temperature difference is large. Due to this thermal stress, the solder joining the electronic components may break on the electronic circuit board. When a break occurs in the solder joint, one or all of the functions of the product are not performed, and it is discovered as a product operation / function stop.

In Patent Document 1, a resistor as a dummy component that does not affect the circuit operation of the electronic component is soldered and mounted on a printed circuit board on which the electronic component (circuit component) is mounted by soldering, and monitoring by this dummy component is performed. A printed circuit board is disclosed. With such a configuration, the printed circuit board described in Patent Document 1 does not require specialized knowledge or special equipment for diagnosing deterioration of the soldered portion, and deteriorates the soldered portion of the mounted electronic component. Makes it possible to diagnose.
JP 2005-109084 A

  However, the printed circuit board described in Patent Document 1 is similar to the electronic component that the installation location actually functions even if the same electronic component that is mounted for actual functioning is mounted as a dummy component. Because of the difference, the breakage limit differs from the electronic component that actually functions. In addition, the provision of dummy parts also causes problems such as increased costs and securing board space.

  The present invention has been made in view of the actual situation as described above, and provides an electronic circuit board capable of reliably detecting whether or not the solder joint between the electronic component and the board is broken. That is the purpose.

  In order to solve the above-described problems, the first technical means of the present invention is a state of a solder joint portion that joins the electronic component to the board in the electronic circuit board on which the electronic component is mounted on the board by solder joint. Is monitored between two points included in the solder joint, and is provided with a monitoring means for detecting breakage.

  According to a second technical means, in the first technical means, the monitoring means monitors a state of a solder joint portion that breaks due to thermal stress of a certain level or more, among the solder joint portions between the substrate and the electronic component. It is characterized by doing.

  According to a third technical means, in the first or second technical means, the electronic component is a microprocessor.

  According to a fourth technical means, in the third technical means, the monitoring means is provided at each of solder joint portions located at four corners of the microprocessor.

  The fifth technical means is characterized in that in any one of the first to fourth technical means, there is provided a detection storage means for storing the fact that the monitoring means has detected breakage.

  The sixth technical means is characterized in that in any one of the first to fifth technical means, there is provided transmission means for transmitting the fact that the monitoring means has detected breakage to the outside.

  According to the present invention, in an electronic circuit board, it can be reliably detected whether or not the solder joint between the electronic component and the board is broken.

  FIG. 1 is a partial cross-sectional view showing a configuration example of an electronic circuit board according to an embodiment of the present invention, in which 1 is an electronic circuit board. An electronic circuit board 1 according to the present invention includes an electronic component 11 mounted on a substrate (referred to as a substrate body) 10 by solder bonding. The electronic circuit board 1 is mounted on an electronic device (electronic device product), and is particularly useful for an electronic device installed outdoors such as a gas meter, a water meter, and a centralized monitoring device.

  FIG. 1 shows an example in which the solder bonding is performed by attaching the solder 12 to the protruding electrodes (bumps) 11a of the electronic component 11, but this is not restrictive. The electronic component 11 and the board body 10 may be joined by the solder 12.

  As a main feature of the present invention, the electronic circuit board 1 includes the following monitoring means 13 on the board body 10. The monitoring means 13 monitors the state (soldered state) of the solder joint 12 that joins the electronic component 11 between two points (A point and B point) included in the solder joint 12 and detects breakage. It is means to do. In FIG. 1, the monitoring unit 13 and its wiring are not shown in the substrate body 10, but as described above, the monitoring unit 13 is also provided on the substrate body 10 in the same manner as the electronic component 11.

  The breakage of the solder joint portion 12 means that what is electrically connected (short) becomes no connection (open). Therefore, the monitoring means 13 periodically measures the voltage or resistance between two points (point A and point B) of one solder joint 12 and when the voltage value or resistance value suddenly increases, What is necessary is just to detect that the solder joint between A point and B point broke. Any one of the two points (point B in this example) may be GND-connected. Further, the monitoring means 13 may generate a pulse signal at regular intervals, and may detect that the solder joint between the points A and B is broken when the pulse signal cannot be confirmed. The number of monitoring means 13 installed is the same as the number of solder joints 12 to be monitored.

  As described above, according to the electronic circuit board 1 of the present invention, since the solder joint 12 of the electronic component 11 that actually functions on the electronic circuit board 1 is to be monitored without using a dummy component, It is possible to reliably detect whether or not the solder joint with the substrate body 10 is broken, that is, whether or not the solder joint is broken at the electronic circuit board 1. Further, since only the monitoring unit 13 is provided rather than providing the dummy part and its monitoring unit, it is easy to reduce costs and secure a board space. Note that notification of the monitoring result will be described later.

  Next, the solder joint 12 that is preferably monitored is described. Since the breakage of the solder joint portion occurs due to the difference in thermal expansion coefficient between the electronic component 11 and the substrate body 10 due to thermal stress such as a temperature change, the difference in thermal expansion coefficient is large and the solder joint portion of the electronic component 11 having a large shape. Break first. From such an empirical rule, an analysis result using actual simulation, or a result of an evaluation test, which solder joint portion of which electronic component 11 breaks earliest in the electronic circuit board 1 of the product. Can predict. And it is preferable to make the solder joint part 12 estimated in that way the monitoring object.

  As described above, the monitoring unit 13 preferably monitors the state of the solder joint 12 that breaks due to thermal stress of a certain level or more among the plurality of solder joints between the substrate body 10 and the electronic component 11. By such monitoring means 13, it is possible to detect the breakage of the solder joint 12 earlier than any other part on the electronic circuit board 1 to be mounted on the product, before the other operation / function of the product is abnormal. it can.

  FIG. 2 is a top view illustrating a configuration example of an electronic circuit board according to an embodiment of the present invention, and is a diagram illustrating an example of the electronic circuit board 1 of FIG. In the figure, reference numeral 12 denotes a microprocessor as an example of an electronic component to be monitored, reference numerals 13a to 13d denote the monitoring means 13 in FIG. 1, and reference numerals 12a to 12d denote solders to be monitored by the monitoring means 13a to 13d, respectively. It refers to the joint (monitoring means 13 in FIG. 1). Other components are denoted by the same reference numerals as in FIG.

  In an electronic circuit board 1 illustrated in FIG. 2, a microprocessor 11 is soldered on a board body 10. Among them, the monitoring means 13a to 13d are connected only to the solder joint portions 12a to 12d joined to the electrode pins at the four corners.

  When the microprocessor 11 is mounted as in the electronic circuit board 1, the microprocessor 11 is an electronic component that performs a particularly important function in the electronic circuit board 1, and among the mounted electronic components, One of the big parts. As in the electronic circuit board 1 of FIG. 2, it is preferable to perform monitoring by determining an electronic component to be monitored (in this example, the microprocessor 11) among the electronic components being used. Further, the microprocessor 11 has a quadrangular shape, and the stress due to thermal stress is greatest at the solder joints 12a to 12d of the electrode pins near the four apexes (four corners). Therefore, the monitoring means 13a to 13d are connected to the solder joint portions 12a to 12d to be monitored. As described above, it is preferable to monitor the breakage of the solder joint by setting a part to be monitored particularly among the electronic components. By such monitoring, it is possible to accurately estimate the time until the microprocessor 11 which is an important part fails.

  As described above, since the solder joint portion of the microprocessor 11 is to be monitored, the solder joint portion predicted to break due to thermal stress is the solder joint portion of the microprocessor 11 (in this example, the solder joint portions 12a to 12d). In some cases, it leads to improved reliability as a fail-safe.

  On the other hand, when the solder joint predicted to break due to thermal stress is an electronic component other than the microprocessor 11, for example, depending on the assumed stress difference between the predicted solder joint and the solder joints 12 a to 12 d, for example, voltage When the value or resistance value indicates a value that is a predetermined value before the value that is detected as “breakage”, it is possible to estimate the breakage of the solder joint that has been predicted to break, thus improving the reliability. Even if the solder joints 12a to 12d of the microprocessor 11 are not the place where the electronic circuit board 1 breaks the earliest, the solder joints of other electronic parts that break the earliest and the large parts of the microprocessor 11 Use in combination with monitoring leads to improved reliability.

  Next, notification of monitoring results will be described with reference to FIG. FIG. 3 is a diagram illustrating a configuration example of an electronic circuit board according to another embodiment of the present invention. In the figure, 14 is a detection storage means, 15 is a transmission means, and the other components are indicated by the same reference numerals as in FIGS. In FIG. 3, it is assumed that a solder joint 12 of an electronic component is connected to the monitoring unit 13.

  As shown in FIG. 3, the electronic circuit board 1 preferably includes a detection storage unit 14 that stores information that the monitoring unit 13 has detected a break (breakage detection information). The detection storage unit 14 can be configured by a memory such as a nonvolatile memory connected to the monitoring unit 13 and a part that controls the storage.

  For example, if the monitoring target is a solder joint part of a microprocessor, the monitoring result is displayed in the microprocessor except for the case where the electrode pin corresponding to the solder joint part that is the monitoring target and the fracture is detected is a power supply pin. May be transmitted. Even if the monitoring target is not a microprocessor, if the microprocessor is mounted on the electronic circuit board 1, the monitoring result may be transmitted to the microprocessor. If none of these applies, the monitoring result may be transmitted to an electronic component equipped with a memory regardless of whether the solder joint is a monitoring target. By providing the detection storage unit 14 in this manner, the fracture detection information can be read from the detection storage unit 14, so that the solder joint has been broken even after a lapse of time since the detection. Can be recognized.

  When the monitoring target is a plurality of solder joints and a plurality of monitoring means 13 are provided, the detection storage means 14 also stores information for identifying the monitoring means 13 as breakage detection information. This is useful for repairs. Moreover, it is preferable that the break detection information includes an occurrence time (occurrence date and time). The date and time may be acquired from an electronic component joined at a solder joint to be monitored, or may be obtained from another electronic component if the electronic component cannot output the date and time. Or you may acquire from another electronic circuit board.

  Further, as shown in FIG. 3, the electronic circuit board 1 preferably includes transmission means for transmitting to the outside that the breakage is detected by the monitoring means 13. The transmission means 15 is means for informing the user that the solder joint has broken on the electronic circuit board 1. The transmission means 15 may be constituted by a communication means such as a telephone line modem or a wireless communication interface, for example, a means for emitting an alarm signal to the outside by turning on an LED (Light Emitting Diode), or a notification sound to the outside. It may be a means to make. If the LED is mounted as the monitoring means 13, it can also serve as the transmission means 15. By providing such a transmitting means 15, it is possible to confirm the breakage of the solder joint portion without observing the electronic circuit board 1, and it is possible to consider a countermeasure before actually opening the electronic device.

  In addition, the transmitting unit 15 may transmit that there is a possibility that the breakage may occur in another place on the electronic circuit board 1 simultaneously with the transmission with the detection of the breakage. By targeting the electronic component that is expected to break the earliest mentioned above, other solder joints on the electronic circuit board, for example, if the function of the electronic component stops, it can be a fatal failure as a product. Thus, it is possible to know before the solder joint breaks, and it is possible to take countermeasures before the function of the part that causes a fatal failure stops.

  Further, it is preferable that the transmission unit 15 is provided with the detection storage unit 14. As a result, one or more pieces of breakage detection information accumulated in the detection storage means 14 can be obtained at a time as required.

It is a partial cross section figure showing the example of composition of the electronic circuit board concerning one embodiment of the present invention. It is a top view which shows the structural example of the electronic circuit board which concerns on one Embodiment of this invention. It is a figure which shows the structural example of the electronic circuit board which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electronic circuit board, 11 ... Electronic component (microprocessor etc.), 11a ... Projection electrode, 12a-12d ... Solder junction part, 13, 13a-13d ... Monitoring means, 14 ... Detection storage means, 15 ... Transmission means.

Claims (6)

  In an electronic circuit board in which an electronic component is mounted on a substrate by solder bonding, the state of a solder joint portion that joins the substrate and the electronic component is monitored between two points included in the solder joint portion, and a break is detected. An electronic circuit board comprising monitoring means.   2. The electronic circuit according to claim 1, wherein the monitoring unit monitors a state of a solder joint portion that is broken by a thermal stress of a certain level or more among solder joint portions between the substrate and the electronic component. substrate.   The electronic circuit board according to claim 1, wherein the electronic component is a microprocessor.   4. The electronic circuit board according to claim 3, wherein the monitoring means is provided at each of solder joint portions located at four corners of the microprocessor.   The electronic circuit board according to any one of claims 1 to 4, further comprising a detection storage unit that stores that the breakage is detected by the monitoring unit.   The electronic circuit board according to any one of claims 1 to 5, further comprising a transmission unit configured to transmit to the outside that a break has been detected by the monitoring unit.

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