JP4375146B2 - Igniter igniter - Google Patents

Description

  The present invention relates to an igniter for an ignition device having a protection resistance against surge.

  The ignition device is used to ignite an ignition plug in a vehicle engine or the like, and generates a high voltage in the secondary coil by interrupting the current from the in-vehicle battery flowing in the primary coil of the ignition coil by the switching element. . Here, a surge (instantaneous overvoltage) may occur in the voltage of the in-vehicle battery, and the igniter may break down. In addition, even when the alternator terminal is disconnected, a surge occurs in the power supply voltage, and if this power supply surge voltage is input to the igniter, a failure may occur.

Therefore, a protective resistor is inserted between the battery and the switching element to keep the current flowing through the switching element small. For example, in a conventional ignition device (see Patent Document 1), as shown in FIG. It is connected to the silicon substrate 100. Then, in preparation for an excessive surge applied to the battery, a resistance element 116 is disposed between the battery terminal 105 and the small terminal 115, and the small terminal 115 and the silicon substrate 100 are connected by wire bonding 118. Yes. Base plate 102 and terminals 105 to 107 are molded with epoxy resin 120.
JP 2001-193617 A

  However, in consideration of an actual manufacturing process, it must be said that it is extremely difficult to mount the small terminal 115 and the resistance element 116 of the conventional example in the illustrated state. That is, before the base plate 102 and the four terminals 105 to 107 and 115 are molded with the epoxy resin 120, it is necessary to position them in a predetermined state. Here, the collector terminal 103 of the base plate 102 and the three terminals 105 to 107 protruding outward can be positioned, for example, by being coupled to each other externally.

  However, the small terminal 115 is inward compared to the three terminals 105 to 107 and the like and cannot be coupled to the battery terminal 105 or the input terminal 106 as it is. Therefore, the posture of the small terminal 115 before the molding becomes unstable. For example, it is conceivable to form an extension projecting outward from the small terminal 115 for coupling, but this increases the outer dimensions of the epoxy resin 120 and thus the igniter.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an igniter for an ignition device in which a protective resistor for limiting a current due to a power supply surge voltage is arranged without increasing its outer dimension.

  The inventor of the present application has come up with the idea that the protective resistor is mounted in, for example, an island shape (island shape) on the lead frame on which the power element and the control element are mounted.

(1) The igniter of the ignition device according to the first invention of the present application is the first lead frame, the power element mounted on the first lead frame, the second lead frame, and the second lead. A control element mounted on the frame and connected to the power source to control the power element, and disposed between the power source and the control element, protects the control element by limiting the power surge voltage and superimposes on the power surge voltage And a protective resistor including a surge limiting portion that absorbs the high-frequency surge . The surge limiting unit includes an insulating substrate placed on the first lead frame or the second lead frame, and a resistor placed on the insulating substrate.

(2) The igniter of the ignition device according to the second invention, as described in claim 3, includes a power element mounted on the first lead frame and the first lead frame, and the second lead frame and the second lead frame. A control element that is mounted on and connected to a power source to control the power element, and is arranged between the power source and the control element to limit the power source surge voltage to protect the control element and to superimpose the power source surge voltage on the high frequency surge And a protective resistor including a surge limiting portion that absorbs . The surge limiting portion has a semiconductor substrate formed on the second lead frame and a diffusion layer diffused in the semiconductor substrate.

(1) According to the igniter of the ignition device according to the first invention of the present application, the surge limiting portion of the protective resistor mounted on the first lead frame or the second lead frame and disposed between the power source and the control element. The power supply surge voltage is limited, and the failure of the control element is prevented. In addition, since the position and posture of the protective resistor arranged on the first or second lead frame is stable without providing a special holding means, there is a concern that the outer dimensions of the igniter may increase due to the arrangement of the protective resistor. Absent. Further, according to this igniter, the surge absorbing portion of the protective resistor can absorb a high-frequency surge superimposed on the power supply surge voltage, thereby preventing a failure of the control element.

(2) According to the igniter of the ignition device according to the second invention, the power supply surge voltage is limited by the surge limiting portion of the protective resistor mounted on the second lead frame and disposed between the power supply and the control element, Failure of the control element is prevented. Further, since the position and posture of the protective resistor arranged on the second lead frame is stabilized without providing any special holding means, there is no fear that the outer dimensions of the igniter increase due to the arrangement of the protective resistor. Further, according to this igniter, the surge absorbing portion of the protective resistor can absorb a high-frequency surge superimposed on the power supply surge voltage, thereby preventing a failure of the control element.

  The igniter of the present invention can be classified into three types according to the configuration of the protective resistor and the relationship between the protective resistor and the lead frame.

(A) First type The first type includes two lead frames. A power element is mounted on the first lead frame, and a control element for controlling the power element is mounted on the second lead frame. A protective resistor is mounted on the first lead frame or the second lead frame (see claim 1). The first lead frame is a high voltage system, and the power element drives an actuator (for example, a primary coil of an ignition coil) by a switching operation or the like, and includes an IGBT and an FET.

  On the other hand, the second lead frame is a GND system, and the control element controls the power element by an external signal, and is composed of, for example, an IC chip.

  The protective resistor mounted on the first lead frame or the second lead frame includes at least a limiting portion that limits a power surge voltage (power surge), and further absorbs a high frequency surge that may be superimposed on the power surge voltage. It may include an absorbing part. The same applies to the second type and the third type.

a. Surge limiting part For example, a thick film resistor can be adopted as the surge limiting part of the protective resistor. Thick film resistors include an insulating substrate, a pair of electrode plates thereon, and a resistor across both electrode plates. The insulating substrate is made of ceramic or the like, and is mounted on the lead frame in an island shape. “Island” means that an insulating substrate having a size smaller than that of the lead frame is mounted near the center away from the periphery of the lead frame. The shape of the insulating substrate may be circular, polygonal or rectangular, and its thickness is determined in consideration of the required withstand voltage. One electrode plate is connected to the power source, and the other electrode plate is connected to the control element.

b. Surge absorbing part As a surge absorbing part, a gap resistor, that is, a kind of capacitor can be constituted by one electrode plate constituting the surge limiting part and an intermediate electrode plate facing the one electrode plate with a small gap in between. . The intermediate plate is connected to GND. In this way, if the surge absorbing portion is formed near the surge limiting portion, a part of the components (here, one electrode plate) can be shared by both. The protective resistor can be mounted on the lead frame after the power element and the control element are mounted on the lead frame.

(B) Second type The second type includes a first lead frame and a power element mounted thereon, a second lead frame and a control element mounted thereon, and a protection mounted on the second lead frame. Consisting of resistance. This configuration is the same as the first type, configuration of the protection resistance that Do different.

  More specifically, a diffused resistor or a polysilicon resistor can be employed as the surge limiting unit. The diffusion resistor may be formed by forming a P-type diffusion layer on an N-type silicon (semiconductor) layer formed in an island shape on the lead frame, or conversely, an N-type diffusion layer is formed on the P-type silicon layer formed in an island shape. It may be formed. The resistance value is determined by the size and depth of the diffusion layer and the impurity concentration in the depth direction (the resistance value increases as the impurity concentration decreases). One end of the diffusion layer may be connected to the power source and the other end connected to the control element.

  The polysilicon resistor is formed by forming a polysilicon layer on an insulating film of a silicon (semiconductor) layer formed in an island shape on a lead frame. The resistance value is determined by the size and depth of the pattern, the polysilicon growth method, the concentration of added impurities (P, N), and the like.

  As the surge absorbing portion, a back-to-back Zener diode structure can be formed by the vertical impurity layer structure of the silicon chip. For example, it includes a P-type layer formed in an island shape, an N-type layer epitaxially grown on the P-type layer, and a P layer diffused therein. The P-type layer on the upper surface, which is one terminal of the resistor, is connected to the power supply by wire bonding, and the GND side on the lower surface is connected to the lead frame with solder. The protective resistor can be formed on the lead frame at the same time as or after forming the power element and the control element on the lead frame.

(C) Third type The third type includes one lead frame. A power element and a control element are mounted on the lead frame, and a protective resistor including a surge limiting unit is mounted. The surge limiting portion includes an insulating substrate placed in an island shape on the lead frame and a resistor mounted on the insulating substrate, and a semiconductor substrate (in the island shape formed on the lead frame) If having N-type layer) and the spreading layer diffused into the semiconductor made substrate and a (P-type layer) and there Ru.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First embodiment>
(Constitution)
The ignition device shown in FIG. 1 includes a primary coil 11 connected to a power source (battery) 10, a secondary coil 14 connected to a spark plug 13, and an igniter 20. As shown in FIG. 2, the igniter 20 includes a mold resin 60, an IGBT chip (power element) 25 and a protection chip (protection resistor) 30 mounted on the first lead frame 22, and a second lead frame 45. And an IC chip (control element) 50 mounted thereon.

  Among these, the mold resin 60 has a rectangular plate shape, in which the first lead frame 22 and the second lead frame 45 are arranged side by side. The first lead frame 22 includes a substantially rectangular main body 23 and an extension 24 extending from one side thereof, and an IGBT chip 25 as a power element is mounted on the main body 23. The extension 24 is connected to the primary coil 14.

  Further, a protective chip 30 is mounted on the main body 23 near the IGBT chip 25. As shown in FIGS. 2 and 3, the protection chip 30 includes a surge limiter 36 for a power supply surge voltage and a surge absorber 41 for a high-frequency surge. The surge limiting portion 36 is a ceramic rectangular substrate 31 placed on the main body portion 23 of the first lead frame 22 and the resistance passed between the one electrode plate 33 and the other electrode plate 34 placed thereon. A body 35. The surge absorbing portion 41 includes a projecting portion 33 a of the one electrode plate 33 and an intermediate electrode plate 38 that is opposed by a small gap 39.

  The second lead frame 45 includes a rectangular main body portion 46 and an extension portion 47 extending therefrom. The main body portion 46 on which the IC chip 50 is mounted is formed by the main body portion 23 and the extension portion 24 of the first lead frame 22. Arranged in the indented compartment. The main body 46 is connected to the IGBT chip 25 by wire bonding 48 and is connected to the intermediate electrode plate 38 by wire bonding 49. The extension 47 is connected to GND, and the IC chip 50 is connected to the other electrode plate 34 of the IGBT chip 25 and the protection chip 30 by wire bonding 52 and 53.

  An ignition signal input lead frame 55 is mounted in a recess defined by the main body 46 and the extension 47 of the second lead frame 45 and connected to the IC chip 50 by wire bonding 56. A predetermined ignition signal is input to the lead frame 55 from the outside. A power supply lead frame 57 is mounted in the recess of the first lead frame 22 along with the second lead frame 45 and the like, and is connected to the one electrode plate 33 of the protection chip 30 by wire bonding 58. Mold resin 60 is filled in the gaps between the first lead frame 22, the second lead frame 45, the external signal input lead frame 55, and the power supply lead frame 57.

(Function)
1 and 2, the IC chip 50 operates based on the ignition signal input from the external signal input lead frame 55 to control the gate signal of the IGBT chip 25. As a result, the current flowing from the battery 10 to the primary coil 11 is abruptly interrupted, and a high voltage generated in the secondary coil 14 due to electromagnetic induction action is applied to the spark plug 13.

  In FIG. 1, the protection chip 30 prevents the power surge voltage generated in the power line 65 from entering the IC chip 50. That is, as shown in FIGS. 2 and 3, the power supply lead frame 57 is connected to the one electrode plate 33 by wire bonding 58, and the other electrode plate 34 is connected to the external signal input lead frame 55 by wire bonding 53. Yes. Here, the resistor 35 limits the current value of the current flowing by the power supply surge voltage to be small.

  On the other hand, a high frequency surge superimposed on the power surge voltage and applied to the one electrode plate 33 is absorbed by the gap 39 between the protrusion 33a of the one electrode plate 33 and the intermediate electrode plate 38, and the intermediate electrode plate 38 and It is discharged to the GND from the extension 47 of the second frame 45 through the wire bonding 49.

(effect)
According to this embodiment, the following effects can be obtained. First, measures against surges are sufficient. The surge limiting part 36 including the resistor 35 limits the power source surge current, and the surge absorbing part 41 including the gap 39 absorbs the high frequency surge. Therefore, the failure of the IC chip 50 through which the limited current flows is prevented.

  In this connection, a thick film resistor can be used as the protective chip 30 and is relatively inexpensive. In addition, since the substrate 31 is made of ceramic and has a predetermined thickness, the gap between the pair of conductive plates 33 and 34 and the conductive first lead frame 22 is easily and reliably maintained at a predetermined dielectric strength or higher. Be drunk.

  Secondly, the protective chip 30 can be arranged at a predetermined position inside the igniter 20 without increasing the size of the igniter 20. This is because the protective chip 30 is arranged in an island shape on the main body portion 23 of the first lead frame 22, so that the position of the protective chip is stabilized without requiring any special holding means.

  In FIG. 2, the protective chip 30 is drawn large for convenience of illustration, but the actual product is much smaller than this. Moreover, the area | region which has arrange | positioned the protection chip | tip 30 on the surface of the main-body part 23 was not utilized effectively conventionally, and was wasted. Therefore, even if the protective chip 30 is disposed, the vertical dimension and the horizontal dimension of the main body 23 are not substantially increased.

<Second embodiment>
4 and 5 show a second embodiment of the present invention. The second embodiment is different from the first embodiment in that a protective chip (protective resistor) 70 including a semiconductor substrate 73 is mounted on the second lead frame 46 in an island shape. The same. In the following, different configurations will be mainly described.

  The protective chip 70 mounted in the vicinity of the IC chip 50 on the second lead frame 46 includes a surge limiting unit 72 and a surge absorbing unit 80. The surge limiting portion 72 includes a P-type semiconductor substrate 81 formed in an island shape on the main body portion 46 of the second lead frame 45, an N-type layer 82 epitaxially grown on the substrate, and a predetermined inside the N-type layer. And a P-type layer (diffusion layer) 74 diffused into a shape. One end of the diffusion layer 74 serving as a resistor is connected to the power supply lead frame 57 by wire bonding 77, and the other end is connected to the control IC chip 50 by wire bonding 78. The GND side is connected to the main body 46 of the lead frame 45 by solder.

  As shown in FIG. 5, the surge absorber 80 includes a back-to-back Zener diode structure 85 (shown by a two-dot chain line in FIG. 1). That is, a back-to-back zener diode structure 85 is formed between the P-type layer 81 and the N-type layer 82 and between the P-type layer 74 and the N-type layer 82. According to the second embodiment, the same effects as the first and second effects of the first embodiment can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is circuit explanatory drawing which shows the whole ignition device containing 1st Example of this invention. It is front sectional drawing which shows the igniter by 1st Example of this invention. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. It is front sectional drawing which shows the igniter by 2nd Example of this invention. FIG. 5 is a sectional view taken along line 5-5 in FIG. It is principal part explanatory drawing which shows a prior art example.

Explanation of symbols

10: battery 11: primary coil 13: spark plug 14: secondary coil 20: igniter 22: first lead frame 25: power element 30: protective resistance 31: substrate 33, 34, 38: electrode plate 35: resistor 36 : Control part 39: Gap 41: Absorption part 45: 2nd lead frame 50: Control element 60: Mold resin

Claims (4)

A first lead frame and a power element mounted on the first lead frame;
A second lead frame, and a control element mounted on the second lead frame and connected to a power source to control the power element;
A protective resistor that is disposed between the power source and the control element, protects the control element by limiting a current caused by a power surge voltage, and includes a surge limiting unit that absorbs a high-frequency surge superimposed on the power surge voltage ; Consists of
The igniter for an ignition device, wherein the surge limiting unit includes an insulating substrate mounted on the first lead frame or the second lead frame, and a resistor mounted on the insulating substrate. . 2. The igniter for an ignition device according to claim 1 , wherein the surge absorbing portion includes the one electrode plate and an intermediate electrode plate facing the one electrode plate with a small gap therebetween. A first lead frame and a power element mounted on the first lead frame;
A second lead frame, and a control element mounted on the second lead frame and connected to a power source to control the power element;
A protective resistor that is disposed between a power supply and the control element, protects the control element by limiting a current caused by a power supply surge voltage, and includes a surge limiting unit that absorbs a high-frequency surge superimposed on the power supply surge voltage; Consisting of
The igniter of an ignition device, wherein the surge limiting portion includes a semiconductor substrate formed on the second lead frame and a diffusion layer diffused in the semiconductor substrate. The igniter for an ignition device according to claim 3 , wherein the surge absorber has a back-to-back zener diode structure.

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