JPH11257196A - Igniter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an electronic part from being damaged caused by shearing stress by reducing shearing stress acting on the electronic part mounted on a substrate of an igniter. SOLUTION: An igniter 10 is provided with a heat sink 12, and insulating plate 14, a substrate 16 on which an electronic part 21 is mounted, and a case 11 for housing respective members. Epoxy resin is filled in the case 11 to form an insulating resin layer 19. The heat sink 12 and the insulating plate 14 are bonded by an adhesive layer 17 made of silicone resin adhesives, and the insulating plate 14 and the substrate 16 are bonded by an adhesive layer 18. Both ends of the substrate 16 are longitudinally extended from respective ends of the insulating plate 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
More particularly, the present invention relates to an igniter for intermittently controlling a next current, in which a substrate on which electronic components are mounted is adhered to a support member with an adhesive, and the periphery of the substrate is covered with an insulating resin layer.

[0002]

2. Description of the Related Art In an ignition system of a spark ignition type internal combustion engine, an igniter is used for intermittently controlling a primary current of an ignition coil. As a conventional igniter, as described in JP-A-64-35082, a substrate on which electronic components such as semiconductor elements are mounted on a support member such as an aluminum die-cast container is used as an adhesive (for example, silicon). (A resin-based adhesive), or, as described in JP-A-4-1472, the periphery of a substrate on which electronic components are mounted is covered with an insulating resin such as a thermosetting resin. Such is known.

FIG. 11 shows a configuration example of such a conventional igniter. As shown in FIG. 1, in the igniter 100, a substrate 1 on which an electronic component 101 is mounted is provided.
02 on a support member 103 such as a heat sink.
4, and the periphery of each member is covered with an insulating resin 105. In this way, the periphery of each member, particularly around the terminals and the soldered portions of the electronic component 101, is covered with the insulating resin 105, so that oxidation of these parts can be prevented, and the durability can be improved.

[0004]

The igniter 100 as described above is generally manufactured as follows. First, an adhesive 110 is applied on the support member 103 as shown in FIG. Next, the substrate 102 on which the electronic component 101 is mounted is bonded to the support member 103 to which the adhesive 110 has been applied. Here, if the amount of the adhesive 110 applied on the support member 103 is large, the adhesive 110 that has protruded from between the substrate 102 and the support member 103 as shown in FIG. Wrap around to cover the end face. Then, as shown in FIG. 3C, the periphery of the substrate 102 is covered with the insulating resin 105 while the end surface of the substrate 102 is covered with the adhesive 110.
The following problems will occur if it is covered by the cover.

That is, since the substrate 102 and the insulating resin 105 covering the substrate 102 usually have different linear expansion coefficients, the substrate 102 and the insulating resin 105 expand or contract in accordance with a change in the temperature of the surrounding environment. At this time, relative displacement occurs between the two members in the longitudinal direction thereof, as indicated by arrows in FIG.

In general, the adhesive 110 (for example, a silicone resin-based adhesive) has an extremely small elastic modulus as compared with the substrate 102 (for example, an alumina substrate) and the insulating resin 105 (for example, an epoxy resin). Therefore, when the end surface of the substrate 102 is covered with the adhesive 110 as described above, the adhesive 110 is elastically deformed, so that the substrate 102 relatively freely expands or contracts in its longitudinal direction. become. When the substrate 102 thermally expands or contracts in this way, the substrate 102
Displacement between the insulating resin 105 and the insulating resin 105 increases, and excessive shear stress may be generated at the interface between the two members 102 and 105. As a result, the conventional igniter 10
In the case of No. 0, such a shear stress may act on the electronic component 101 mounted on the substrate 102, particularly on its legs, and cause damage to the electronic component 101.

The present invention has been made in view of such circumstances, and has as its object to reduce shear stress acting on an electronic component mounted on an igniter substrate and prevent damage to the electronic component caused by the shear stress. Is to do.

[0008]

According to a first aspect of the present invention, a substrate on which electronic components are mounted, a supporting member for supporting the substrate, and the substrate and the supporting member are bonded. An igniter comprising an adhesive layer and an insulating resin layer covering the periphery of a substrate, wherein the igniter further comprises a regulating means for regulating the adhesive from protruding from between the substrate and the support member and reaching the end face of the substrate. It is assumed that.

An igniter having the above configuration is generally manufactured as follows. First, the substrate is bonded and integrated on the support member with an adhesive layer, and then housed in, for example, a case. Then, an insulating resin layer covering the periphery of the substrate and the supporting member is formed by filling and curing the liquid insulating resin in the case.

Here, according to the above configuration, even if the adhesive overflows from between these members when the substrate is adhered to the support member, the adhesive which has overflowed by the regulating means does not adhere to the substrate. Reaching the end face is regulated. Therefore, since the end surface of the substrate is reliably covered with the insulating resin layer, the relative positional change generated between the substrate and the insulating resin layer is reduced.

According to a second aspect of the present invention, in the igniter according to the first aspect, the gist is that the restricting means is an end portion of the substrate extending from an end portion of the support member.

According to the above configuration, since the end of the substrate is extended from the end of the support member, the extended end suppresses the adhesive from flowing around the end surface of the substrate. Therefore, similarly to the operation of the first aspect, the end face of the substrate is reliably covered with the insulating resin layer, and the relative positional change generated between the substrate and the insulating resin layer is reduced. .

According to a third aspect of the present invention, in the igniter according to the first aspect, the regulating means is a recess formed near the end of the substrate on the supporting member.

According to the above configuration, since the concave portion is formed near the end of the substrate on the support member, the adhesive that has protruded from between the substrate and the support member permeates into the concave portion. Therefore, similarly to the operation of the first aspect, the end face of the substrate is reliably covered with the insulating resin layer, and the relative positional change generated between the substrate and the insulating resin layer is reduced. .

According to a fourth aspect of the present invention, in the igniter according to the first aspect, the gist is that the restricting means is a convex portion that is provided on the supporting member and abuts on the end surface of the substrate. .

According to the above configuration, since the convex portion is provided on the support member and the convex portion is brought into contact with the end surface of the substrate, the adhesive protrudes from between the support member and the substrate. Is suppressed. Therefore, similarly to the operation of the first aspect, the end face of the substrate is reliably covered with the insulating resin layer, and the relative positional change generated between the substrate and the insulating resin layer is reduced. .

Further, according to the above configuration, the work of positioning the substrate on the support member is facilitated by bonding the substrate to the support member with its end face in contact with the projection.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an igniter 10 according to this embodiment.
FIG. 2 shows a cross section taken along line 2-2 in FIG. FIG. 3 is an exploded perspective view showing components of the igniter 10, and FIG. 4 is an enlarged view of the vicinity of a rear end of a ceramic substrate 16 described later. FIG.
In the figure, illustration of an insulating resin layer 19 described later is omitted.

As shown in these figures, the igniter 10
The case 11 is formed in a bottomed rectangular cylindrical shape having a housing space 11a by, for example, a PBT (polybutylene terephthalate) resin, a PPS (polyphenylene sulfide) resin, or the like. A plate-like heat sink 12 made of a metal material such as copper or aluminum is provided in the housing space 11a. A mounting groove 11b is formed in the case 11, and a peripheral portion of the heat sink 12 is inserted into the mounting groove 11b.

On the upper part of the heat sink 12, the case 1
Similarly to 1, an insulating plate 14 made of PPS resin or the like is provided. The insulating plate 14 has a rectangular plate-shaped fixing portion 14a, a first support portion 14b extending downward from a front end (the left side in FIGS. 1 to 3) of the fixing portion 14a, and left and right sides of the fixing portion 14a. A pair of second support portions 14c protruding upward from the ends. The lower surface of the fixing portion 14a is bonded to the upper surface of the heat sink 12 via an adhesive layer 17 made of a silicone resin-based adhesive. The first support portion 14b is in contact with the side surface of the heat sink 12.

A rectangular plate-shaped ceramic substrate (hereinafter abbreviated as "substrate") 16 is adhered to the upper surface of the fixing portion 14a via an adhesive layer 18 made of a silicone resin-based adhesive. Left and right (up and down in FIG. 1) side surfaces of the substrate 16 are in contact with the respective second support portions 14c.

On the other hand, both front and rear ends of the substrate 16 extend from the respective ends of the fixing portion 14a. Substrate 16
A plurality of terminals 25 are soldered to the extended front end, and the terminals 25 are similarly soldered to the upper surface of the heat sink 12. The ends of the terminals 25 protrude from the opening of the case 11, and the protruding portions are connected to a control device (not shown) (not shown).

On the upper surface of the heat sink 12, a power transistor 20 is provided adjacent to the substrate 16. The heat sink 12 is a heat dissipating member of the power transistor 20 and also functions as a collector electrode of the transistor 20. An electronic component 21 such as an IC or a capacitor is provided on the upper surface of the substrate 16, and a thick film resistor and a wiring pattern (not shown) are printed on the lower surface thereof. These thick film resistors and wiring patterns are insulated from the heat sink 12 by the insulating plate 14. These power transistor 20 and electronic component 2
1. An electric circuit for interrupting a primary current of an ignition coil (not shown) by a thick film resistor or the like is configured.

An insulating resin layer 19 is formed in the housing space 11a by filling and curing an epoxy resin.
The periphery of the electronic component 21, the insulating plate 14, the heat sink 12, and the like mounted thereon are covered.

A manufacturing process of the igniter 10 having the above configuration will be schematically described with reference to FIG. First, after applying an adhesive to the lower surface of the fixing portion 14a of the insulating plate 14, the fixing portion 14a is placed on the upper surface of the heat sink 12, and the insulating plate 14 and the heat sink 12 are bonded.

Next, an adhesive is similarly applied to the upper surface of the fixing portion 14a. Then, the substrate 16 is placed on the upper surface of the fixing portion 14a such that the left and right side surfaces of the substrate 16 on which the electronic components 21 are mounted and the terminals 25 are soldered are brought into contact with the respective second support portions 14c. The substrate 16 and the insulating plate 14 are bonded.

After the insulating plate 14 and the substrate 16 are fixed to the heat sink 12 as described above, the terminals 25 are soldered to the front end of the substrate 16 and the upper surface of the heat sink 12, and the electrical The circuit and the power transistor 20 are connected by wire bonding.

Next, while inserting the peripheral portion of the heat sink 12 into the mounting groove 11b of the case 11,
2 is accommodated in the accommodation space 11a. Then, the accommodation space 1
1a is filled with a liquid epoxy resin, and the case 11 is heated to a predetermined temperature to cure the filled epoxy resin to form an insulating resin layer 19.

As described above, in the igniter 10 according to the present embodiment, the front and rear ends of the substrate 16 are
Each of the end portions 4a is extended from each end.
Therefore, as shown in FIG. 4, even if the adhesive applied to the upper and lower surfaces of the fixing portion 14 a may protrude from the rear end of the fixing portion 14 a, It is regulated that the adhesive wraps around the rear end surface of the substrate 16. Similarly, the protruding adhesive does not run around the front end surface of the substrate 16.

(1) Therefore, according to the present embodiment, the front and rear end faces of the substrate 16 are surely covered with the epoxy resin filled in the case 11, so that they are insulated from the substrate 16 in the front and rear direction. The relative change in position between the resin layer 19 and the resin layer 19 is reduced. As a result, the substrate 1
The shear stress generated at the interface between the insulating resin layer 6 and the insulating resin layer 19 can be reduced to prevent the electronic component 21, particularly its legs, from being damaged by the shearing force, and the durability of the igniter 10 can be reduced. In addition, reliability can be dramatically improved.

(2) Further, in the present embodiment, the fixing portion 14
The left and right side surfaces of the substrate 16 contact the second support portion 14c when the substrate 16 is bonded to the fixed portion 14a, while the second support portion 14c is projected upward from each of the left and right ends of the substrate a. I try to make it. Therefore, it is possible to prevent the adhesive applied to the fixing portion 14a from protruding from the left and right sides of the substrate 16.

Therefore, according to the present embodiment, the left and right end surfaces of the substrate 16 are not covered with the adhesive.
The same substrate 16 is used not only in the front-back direction but also in the left-right direction.
And the relative position change amount generated between the insulating resin layer 19 and the insulating resin layer 19 is reduced. As a result, it is possible to more reliably prevent the electronic component 21 from being damaged due to shear stress generated at the interface between the substrate 16 and the insulating resin layer 19.

(3) According to the present embodiment, even if the adhesive protrudes from between the fixing portion 14a and the substrate 16, there is no possibility that the electronic component 21 is damaged. When applying the adhesive to the lower surface, it is not necessary to strictly control the application area and the application amount. Therefore, the manufacturing process of the igniter 10 can be simplified, and the manufacturing cost can be reduced.

(4) Further, according to the present embodiment, the substrate 1
By making the left and right end surfaces of 6 abut on the second support portion 14c, the work of positioning the same substrate 16 on the insulating plate 14 can be easily performed.

Second Embodiment Next, a second embodiment will be described with reference to FIGS. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 5 shows an igniter 10 according to this embodiment.
6 shows a section taken along line 6-6 in FIG. FIG. 7 shows the vicinity of the rear end of the substrate 16 in an enlarged manner. In FIG. 5, the illustration of the insulating resin layer 19 is omitted.

As shown in these figures, in the present embodiment, the rear end of the substrate 16 is not extended from the rear end of the insulating plate 14, and the rear end surfaces of both members 14, 16 are flush. The lower surface on the rear end side of the substrate 16 is covered with a fixing portion 14 a of the insulating plate 14. Also,
On the upper surface of the heat sink 12, a groove 12a having a rectangular cross section is formed extending from the left end to the right end of the substrate 16 between the rear end of the fixing portion 14a and the power transistor 20.

According to the present embodiment having the above-described configuration, in addition to the effects described in (2) to (4) in the first embodiment, the following (5) can be obtained. Thus, it is possible to achieve the following advantageous effects.

(5) That is, according to the present embodiment, the substrate 1
6, the groove 12a is formed in the vicinity of the rear end, so that the adhesive applied to the upper and lower surfaces of the fixing portion 14a protrudes from the rear end of the fixing portion 14a as shown in FIG. In any case, the adhesive that has protruded is
a.

Therefore, according to the present embodiment, since the rear end face of the substrate 16 is surely covered with the epoxy resin, the relative length generated between the substrate 16 and the insulating resin layer 19 in the front-back direction. The amount of change in position is reduced.
As a result, the shearing stress generated at the interface between the substrate 16 and the insulating resin layer 19 can be reduced, and damage to the electronic component 21 due to this shearing force can be prevented, and the durability and reliability of the igniter 10 can be reduced. It can be dramatically improved.

The embodiment described above can be implemented by changing its configuration as follows. In the second embodiment, the rear end of the fixing portion 14a is flush with the rear end of the substrate 16 to cover the entire lower surface. However, as shown in FIG. Both corners on the rear end side may be formed obliquely.
With this configuration, when the liquid epoxy resin is filled in the housing space 11a, the epoxy resin easily flows, and the resin can be filled without gaps over the details of the case 11 such as the groove 12a. Become.

The configuration in which the groove 12a in the second embodiment is further added to the configuration in the first embodiment may be adopted. That is, as shown in FIG. 9, the rear end of the substrate 16 extends from the rear end of the insulating plate 14, and the upper surface of the heat sink 12 near the rear end of the insulating plate 14 has the same shape as the groove 12a. A groove 12b extending in the left-right direction of the substrate 16 is formed. According to such a configuration, even if a large amount of adhesive protrudes from between the heat sink 12, the insulating plate 14, and the substrate 16, it is ensured that the adhesive wraps around the rear end surface of the substrate 16. Can be prevented.

In the second embodiment, the heat sink 1
Although the groove 12a for injecting the adhesive that has protruded from the upper surface 2 is formed, the groove may be formed in the insulating plate 14. That is, as shown in FIG. 10, the rear end of the fixing portion 14a is extended from the rear end of the substrate 16, and the groove 14d is formed near the rear end of the substrate 16 in the extended portion.
To form With this configuration, since the adhesive that has protruded from between the substrate 16 and the insulating plate 14 enters the groove 14d, the adhesive wraps around the rear end surface of the substrate 16 as in each of the above embodiments. Can be prevented.

In the above embodiments, the adhesive is applied to the upper and lower surfaces of the fixing portion 14a of the insulating plate 14 when the insulating plate 14 and the substrate 16 are disposed on the heat sink 12. After applying the adhesive to the upper surface or the lower surface of the substrate 16, the heat sink 12 and the substrate 16 may be bonded to the fixing portion 14a.

In the above embodiments, the heat sink 12
Although the substrate 16 is bonded to the upper surface of the insulating plate 14 disposed thereon, the igniter to which the present invention is applied is not necessarily limited to such a configuration. For example, the present invention may be applied to a configuration in which the insulating plate 14 is omitted and the substrate 16 is bonded on the heat sink 12 by an adhesive.

In each of the above embodiments, the substrate 16 is formed of ceramic and the insulating plate 14 is formed of resin material.
The insulating plate 14 may be formed of a material other than a resin such as alumina. Also, the case 11 may be formed of a metal material, for example.

The embodiments of the present invention and the modifications thereof have been described above. The technical ideas that can be grasped from each of these embodiments will be described together with their effects. (1) a heat sink, an insulating plate provided on the heat sink, a substrate provided on the insulating plate on which electronic components are mounted, an adhesive layer for bonding the insulating plate and the substrate, An igniter comprising an insulating resin layer covering the periphery of the substrate, wherein the end of the substrate is extended from the end of the insulating plate, and a recess is formed on the heat sink near the end of the insulating plate. Features.

According to the above configuration, even when the adhesive may protrude between these members when the substrate is bonded to the insulating plate, the protruding adhesive is applied to the end of the stretched substrate. As a result, it is possible to restrict the wraparound of the end face and to penetrate into the concave portion formed on the heat sink.

Therefore, since the end surface of the substrate is not covered with the adhesive but is surely covered with the insulating resin layer, the relative positional change generated between the substrate and the insulating resin layer is reduced. I do. As a result, the shear stress generated at the interface between the substrate and the insulating resin layer can be reduced, and the electronic components can be prevented from being damaged due to this shear force.

[0051]

According to the first to fourth aspects of the present invention, the adhesive which has protruded from between the members is restricted from reaching the end face of the substrate, and the end face is reliably covered with the insulating resin layer. Therefore, the relative position change amount generated between the substrate and the insulating resin layer is reduced. As a result, the shear stress generated at the interface between the substrate and the insulating resin layer can be reduced, and the electronic components can be prevented from being damaged due to this shear force.

According to the fourth aspect of the present invention, since the substrate can be bonded to the support member while the end surface of the substrate is in contact with the projection, the positioning operation of the substrate on the support member is facilitated. Can be done.

[Brief description of the drawings]

FIG. 1 is a sectional view of an igniter according to a first embodiment.

FIG. 2 is a sectional view taken along the line 2-2 in FIG. 1;

FIG. 3 is an exploded perspective view showing components of the igniter.

FIG. 4 is an enlarged sectional view showing a rear end portion of the substrate.

FIG. 5 is a sectional view of an igniter according to a second embodiment.

FIG. 6 is a sectional view taken along the line 6-6 in FIG. 5;

FIG. 7 is an enlarged sectional view showing a rear end portion of the substrate.

FIG. 8 is a cross-sectional view of an igniter according to another embodiment.

FIG. 9 is an enlarged cross-sectional view illustrating a rear end portion of a substrate according to another embodiment.

FIG. 10 is an enlarged sectional view showing a rear end side portion of a substrate according to another embodiment.

FIG. 11 is a sectional view of a conventional igniter.

FIG. 12 is an explanatory view schematically showing a manufacturing process of the igniter.

[Explanation of symbols]

10 igniter, 11 case, 11a accommodation space,
11b mounting groove, 12 heat sink, 12a, 12b
... Groove, 14 ... Insulating plate, 14a ... Fixed part, 14b ...
1st support part, 14c ... 2nd support part, 14d ... groove, 16 ...
Substrate, 17 adhesive layer, 18 adhesive layer, 19 insulating resin layer, 20 power transistor, 21 electronic component, 25
…Terminal.

Claims (4)

[Claims] A substrate on which an electronic component is mounted; a support member for supporting the substrate; an adhesive layer for bonding the substrate and the support member; and an insulating resin layer for covering the periphery of the substrate. In the igniter, the igniter may further include a restricting unit that restricts the adhesive from protruding from between the substrate and the support member and reaching an end surface of the substrate. 2. The igniter according to claim 1, wherein said regulating means is an end of said substrate extending from an end of said support member. 3. The igniter according to claim 1, wherein said restricting means is a recess formed on said support member near an end of said substrate. 4. The igniter according to claim 1, wherein said restricting means is a convex portion protruding from said support member and abutting against an end surface of said substrate.