JP2012148294A - Device and method for preventing short-circuit fault - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for preventing a short-circuit fault, which effectively prevents a short-circuit fault caused by a whisker, and to provide a method for preventing a short-circuit fault.SOLUTION: The device for preventing a short-circuit fault includes: a short-circuit detecting element 2 mounted in a substrate 31 and having a distance between adjacent terminals thereof, which is set smaller than the least space between conductors adjacent to each other in the substrate 31; a detection means for detecting a short-circuit based on a detection result of the short-circuit detecting element 2; and a vibration imparting means for imparting vibrations to the substrate when the detection device detects a short-circuit.

Description

  The present invention relates to a short-circuit fault prevention device and a short-circuit fault prevention method suitable for application to electronic equipment such as an ECU (Electronic Control Unit).

  Conventionally, in wiring connection inside an ECU or other electronic devices, or wiring connection between electronic devices, a terminal having a plated surface and solder by appropriate means such as reflow or manual soldering have been used. . In general, plating and solder have the property that, except for some materials, a beard-like metal crystal is generated from the surface and grows. This metal crystal is called a whisker, and when this whisker grows, there is a concern that a short circuit failure may occur between terminals or between wirings, resulting in malfunction or failure of the device.

  This whisker varies depending on the ambient temperature, humidity and other conditions, the residual stress in the solder, the surface oxidation degree, etc. It is generally difficult to predict whether a failure will occur after a certain period of time has passed. In addition, with recent lead-free soldering, this whisker tends to grow from a needle shape from tin. As an attempt to prevent such problems due to whiskers, for example, a technique described in Patent Document 1 below has been proposed.

  In this prior art, a circuit using a relay capable of selectively applying a high voltage is incorporated in a place where whisker is expected to grow, and when an abnormality occurs, the place where the whisker is expected to grow is high. It has been proposed to apply a voltage to melt and cut whiskers.

JP 2007-90354 A

  However, in such a conventional technique, in order to remove whiskers, a dedicated circuit using a relay sequence is separately required, and a high potential difference is applied to a predicted location to other electronic components. There is concern about an adverse effect, and further, it is necessary to incorporate the above-described circuit from the beginning after determining a predicted location in advance. That is, the above-described conventional technique has a problem that it is not possible to provide a countermeasure for preventing a problem caused by a whisker that is more versatile and does not cause an increase in cost.

  An object of this invention is to provide the short circuit failure prevention apparatus and short circuit failure prevention method which can prevent the short circuit failure of the adjacent terminal and wiring resulting from a whisker effectively in view of the said problem.

In order to solve the above problem, the short-circuit fault prevention device according to the present invention is:
A short-circuit detecting element mounted in a substrate and having an adjacent terminal distance less than a minimum distance between adjacent conductors in the substrate;
Detection means for detecting a short circuit based on the detection result of the short detection element;
Vibration applying means for applying vibration to the substrate when the detecting means detects the short circuit.

In order to solve the above problems,
The short circuit failure prevention method according to the present invention is:
A detection step for detecting growth exceeding a predetermined limit of the whisker;
The vibration applying step of applying vibration to a component to which the whisker belongs when the growth is detected in the detecting step.

  ADVANTAGE OF THE INVENTION According to this invention, the short circuit failure prevention apparatus and short circuit failure prevention method which can prevent the short circuit failure resulting from a whisker effectively can be provided.

It is a schematic diagram shown about embodiment of the short circuit failure prevention apparatus 1 of the Example which concerns on this invention. It is a schematic diagram which shows the specific form of the terminal arrangement | sequence aspect of the short detection element 2 which detects the short circuit resulting from the whisker of the short circuit failure prevention apparatus 1 of an Example. It is a schematic diagram which shows the specific arrangement | positioning aspect in the board | substrate 31 of direct mounting ECU3 of the short detection element 2 of the short circuit failure prevention apparatus 1 of an Example. It is a schematic diagram which shows the generation | occurrence | production growth aspect of a whisker of the short circuit failure prevention apparatus 1 of an Example, and the detection aspect of a short circuit. It is a schematic diagram which shows the control content of the short circuit failure prevention apparatus 1 of the Example which concerns on this invention with a flowchart.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, a short circuit failure prevention device 1 according to an embodiment of the present invention includes a short circuit detecting element 2, a direct mounting ECU 3 mounted directly on an engine (not shown), and an EFIECU 4 (Electronic Fuel Injection Electronic Control Unit). And the actuator 5. The direct mounting ECU 3 and the EFI ECU 4 are connected to each other by a communication standard such as CAN (Controller Area Network).

  The direct mounting ECU 3 includes, for example, a CPU, a ROM, a RAM, an EEPROM, and a data bus connecting them, and includes a closed circuit including the above-described short-circuit detecting element 2 in the A / W design, and is stored in the ROM. In accordance with the program, the CPU performs the following processing to constitute detection means 3a for detecting a short circuit between adjacent terminals of the short detection element 2.

  The EFIECU 4 is also composed of, for example, a CPU, a ROM, a RAM, an EEPRON, and a data bus connecting them, and according to a program stored in the ROM, the CPU performs predetermined processing described below, and the detection means 3a is short-circuited. It constitutes a vibration applying means 4a that generates a vibration when detected.

  Here, the actuator 5 is an engine, and includes a plurality of pistons incorporated in a cylinder block (not shown). These pistons are connected to a crankshaft via a plurality of corresponding connecting rods, and the plurality of connecting rods are crankshafts. It is connected to the shaft.

  The vibration applying means 4a of the EFI ECU 4 controls the valve lift amount of the intake valve and the exhaust valve built in the cylinder head located at the top of the cylinder block, and controls the valve timing. Further, the vibration applying means 4a changes the valve timing and the valve lift amount to predetermined values that cause knocking. Typically, the predetermined value is a value obtained by shifting the valve timing of the intake valve to the retard side from the normal operation region, and is a value obtained by reducing the valve lift amount from the normal operation region. Belongs to an area.

  Knocking is a phenomenon in which combustion occurs not by ignition of the spark plug in the combustion chamber formed between the cylinder block and the piston, and the engine generates a metal hitting sound or striking vibration in general. Point to.

  As illustrated in FIG. 2, the short-circuit detecting element 2 includes a plurality of terminals 21 to 24 that protrude in the left-right direction from a housing made of, for example, an insulating synthetic resin. Note that the housing does not have an internal circuit. As shown in FIG. 3, the short-circuit detecting element 2 is disposed, for example, at the lower left of the ECU board 31 (board) that constitutes the direct mounting ECU 3 described above.

  As shown in FIG. 3, control elements 32 to 35 are mounted on the ECU board 31. In this embodiment, the adjacent terminals included in the short-circuit detecting element 2 shown in FIG. 2 are made of the same material as the adjacent conductors in the direct mounting ECU 3 (substrate), that is, the terminals included in the control elements 32 to 35. .

  Further, when there are a plurality of types of adjacent conductor materials included in the control elements 32 to 35 illustrated in FIG. 3, for each adjacent terminal included in the short-circuit detection element 2 illustrated in FIG. 22 and terminals 23 and 24) correspond to a plurality of types of materials. For example, when there are two types of materials A and B, the terminals 21 and 22 are the material A, and the terminals 23 and 24 are the material B.

  Further, in this embodiment, the distance between the terminal 21 and the terminal 22 of the short-circuit detecting element 2 shown in FIG. 2, that is, the adjacent terminal distance d is determined by the mutual conductors in the ECU board 31 of the direct mounting ECU 3. It is less than the minimum interval between. That is, the adjacent terminal distance d is set to be smaller than the minimum value among the distances between adjacent terminals included in the control elements 32 to 35 described above.

  In the short-circuit detecting element 2, whisker Wh is generated on the surface of the terminal as shown in the left of FIG. 4 and grows as shown in the center of FIG. When the whisker Wh is short-circuited between adjacent terminals in the process of reaching, it functions as a switch that outputs ON as a detection result. The detection means 3a of the direct mounting ECU 3 described above detects that a short circuit has occurred when the detection result of the short detection element 2 is ON.

  That is, in the short-circuit failure preventing apparatus 1 according to the present embodiment, the short-circuit detecting element 2 that is mounted in the ECU board 31 and has an adjacent terminal distance d that is less than the minimum distance between adjacent conductors in the ECU board 31; The detection means 3a that detects a short circuit based on the detection result of the short-circuit detection element 2 and the vibration application means 4a that applies vibration to the ECU board 31 when the detection means 3a detects a short circuit are configured. The

  The processing contents of the ECU that realizes the control contents described above will be described with reference to the flowchart of FIG. In step S1, the detection means 3a detects the output as the detection result of the short-circuit detection element 2, and in step S2, the detection means 3a determines whether or not a short circuit has occurred due to the output being turned on.

  If it is determined negative in step S2, the process returns to the step before step S1, and if it is determined positive, the process proceeds to step S3.

  In step S3, the vibration applying unit 4a outputs an operation command for causing knocking to the actuator 5, and in step S4, the actuator 5 causes knocking to apply vibration to the ECU board 31.

  In steps S1 and S2, a detection step for detecting growth exceeding the predetermined limit of the whisker is executed. In steps S3 and S4, if growth exceeding the predetermined limit of the whisker is detected, the part to which the whisker belongs, that is, the ECU A vibration applying step for applying the vibration to the substrate 31 is executed, and the short circuit failure prevention method of the present invention is executed.

  According to the present embodiment realized by the control content and the processing content described above, the following operational effects can be obtained.

  That is, the short-circuit detecting element 2 whose adjacent terminal distance d is less than the minimum distance between adjacent conductors in the ECU board 31 is mounted in the ECU board 31, and the detection means 3a of the direct mounting ECU 3 is used as the short-circuit detecting element. By detecting a short circuit between the terminals due to the occurrence and growth of whiskers based on the detection result of 2, the growth exceeding the predetermined limit of whiskers can be detected more accurately.

  That is, whiskers that are assumed to be generated between adjacent terminals included in the control elements 32 to 35 in the ECU board 31 are short-circuited to the short-circuit detecting element 2 before reaching the opposing terminals. Based on this, it can be detected that the whisker is growing beyond a predetermined limit.

  Based on this advance and accurate whisker growth detection, the vibration applying means 4a applies a vibration to the ECU board 31 by utilizing the knocking phenomenon of the engine. All whiskers generated in the elements 32 to 35 can be cut and dropped. Thereby, in the control elements 32-35, the malfunction by a short circuit can be prevented more effectively and reliably.

  Further, the adjacent terminal included in the short-circuit detecting element 2 is made of the same material as the adjacent conductor in the ECU board 31, so that the generation and growth degree of whiskers in the short-circuit detecting element 2 can be controlled. The accuracy in detecting that the above-described whisker has grown beyond a predetermined limit can be further increased by approximating the whisker within .about.35.

  Further, when there are a plurality of types of adjacent conductor materials in the ECU board 31, the above-described whisker is limited to a predetermined limit by corresponding to a plurality of types of materials for each adjacent terminal included in the short-circuit detecting element 2. Therefore, it is possible to further improve the accuracy in detecting that the growth has exceeded.

  Further, in this embodiment, an engine that is an existing vibration source is used, a dedicated circuit using a relay sequence for removing the whisker is unnecessary, and a place where the occurrence of whisker is predicted is high. Since it is unnecessary to apply a potential difference, it is possible to prevent adverse effects on other electronic components. Furthermore, in this embodiment, since it is not necessary to determine in advance the location where whisker generation is predicted, it is possible to provide countermeasures for preventing problems that are more versatile and do not increase costs.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions are made to the above-described embodiments without departing from the scope of the present invention. be able to.

  For example, in the embodiment described above, the vibration source is an engine and knocking based on changes in valve lift and valve timing is used. Instead, the vibration source is a transmission and the shift position is appropriately changed. It is also possible to use a shift shock based on the Alternatively, an air conditioner compressor or the like can be used as a vibration source.

  According to the present invention, it is possible to more accurately prevent a short-circuit failure caused by whisker growth by accurately detecting an event that is a precursor of a short-circuit failure due to a whisker by adding a relatively minor configuration. Since a short circuit failure prevention device and a short circuit failure prevention method that can be provided can be provided, the present invention is useful when applied to various vehicles such as passenger cars, trucks, and buses.

1 Short-circuit failure prevention device 2 Short-circuit detection element 21 Terminal (Material A)
22 Terminal (Material A)
23 Terminal (Material B)
24 Terminal (Material B)
3 Direct mounting ECU
3a Detection means 31 ECU board (board)
32-35 Control elements 4 EFIECU
4a Vibration imparting means 5 Actuator (engine)

Claims (4)

  A short-circuit detecting element mounted in the substrate and having an adjacent terminal distance that is less than a minimum distance between adjacent conductors in the substrate; and a detecting unit that detects a short circuit based on a detection result of the short-circuit detecting element; And a vibration applying means for applying vibration to the substrate when the detecting means detects the short circuit.   The short-circuit failure prevention device according to claim 1, wherein an adjacent terminal included in the short-circuit detecting element is made of the same material as an adjacent conductor in the substrate.   The short-circuit fault prevention device according to claim 2, wherein when there are a plurality of types of materials of the adjacent conductors, the adjacent terminals correspond to the plurality of types of materials.   A detection step for detecting growth exceeding a predetermined limit of whiskers, and the vibration applying step for applying vibration to a part to which the whisker belongs when the growth is detected in the detection step. How to prevent short circuit failure.

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