JPH0749791B2 - Ignition device for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ignition device for an internal combustion engine used in an automobile or the like.

2. Description of the Related Art In a conventional ignition device for an internal combustion engine, as shown in FIGS. 19 and 20, a power transistor 51 and an avalanche diode 52 are separately provided on a heat dissipation substrate 53 via an insulating plate 54 and a heat spreader 55. It is mounted as a bare chip. The power transistor 51 and the avalanche diode 52 are connected to a bonding pad 57 mounted on the substrate 53 by a bonding wire 58 soldered to each other.

Also, as an amplification / switching circuit, a
0, 61, the IC chip 62, and the like are connected to a conductive pattern portion 63 formed on the substrate 53, and this is covered with a silicon resin 64.

The pattern portion 63 is connected by an insert terminal 66 and a lead terminal 67 that are integrally molded with the case 65. The lead terminals 67 are soldered and connected one by one.

Reference numeral 70 indicates a cover, reference numerals 71 and 72 indicate sems screws and nuts, respectively, and reference numerals 73 and 74 indicate power supply lines and collector lines, respectively.

Problems to be Solved by the Invention However, the conventional ignition device has the following problems.

(1) Since the power transistor 51, the IC chip 62, and the solder joints of each of them are coated with the silicon resin 64, the sealing of each of these components and each solder joint from the external atmosphere is not sufficient. Radiation of heat generated from each component will be insufficient. Insulation plate 54,
Since there is a difference in thermal expansion coefficient between the heat dissipation base 53, the power transistor 51, etc., each solder joint part is deteriorated due to thermal fatigue. Particularly in the case of an ignition device directly attached to an internal combustion engine, deterioration due to thermal fatigue is severe.

(2) Since there is a difference in thermal expansion coefficient between the silicon resin 64 and the bonding wire 58, the bonding wire 58 may be broken due to thermal fatigue.

(3) Due to the reasons (1) and (2) above, the humidity resistance and thermal fatigue resistance of the ignition device are lowered, and the reliability of the ignition device is greatly lowered.

(4) Since the number of parts is large and the number of soldering steps is large and the positioning of the lead terminal 67 is performed by hand, pliers work is required, and the quality of the molded product becomes uneven and the manufacturing cost is high. It gets expensive. Further, since the lead terminals 67 are all connected by soldering, the heat resistance is poor.

(5) Since the resistor 69 is attached to the outside of the case 65, the external dimensions of the ignition device are increased and the resistance is increased.
69 is easily damaged by external force, and the solder joint part is easily deteriorated by the external atmosphere. Therefore, the reliability of the ignition device is reduced.

The present invention is intended to solve such problems, and an object thereof is to provide an ignition device for an internal combustion engine, which has improved reliability and stable quality.

Means for Solving Problems Built-in lead frame in which a plurality of lead terminals having steps formed by bending are integrally connected, and the lead terminals connected to the lead frame and an amplification / switching circuit Fully integrated package type
A substrate on which the IC is fixed, and a heat dissipation base on which the substrate individually divided by cutting the lead frame is mounted,
A case having an insert terminal that is combined with this heat dissipation base and fixed to the lead terminal divided into individual pieces by cutting the lead frame, and the surface of the built-in element is protected by a coating material, and the thermal expansion of the coating material The power transistor is fully packaged with an epoxy resin whose ratio is substantially equal to that of the power transistor.

Action In the above ignition device for an internal combustion engine, the number of parts is reduced,
Since the number of connecting parts between parts is reduced, the failure of each part due to temperature change is greatly reduced.

Further, since the resistor is provided in the main body of the apparatus, it is possible to prevent the damage and deterioration of the connection portion due to the external atmosphere.

Example 1 FIG. 1 is a plan view showing an internal combustion engine ignition device of the present invention, and FIG. 2 is a partially cutaway side view of the ignition device shown in FIG.

The power transistor 1 is configured as a full package type in which an avalanche diode is incorporated, and is fixed on the heat dissipation base 2. Of the three terminals 3, 4 of the power transistor 1, a collector terminal 4 and a base terminal 5
Is fixed by welding to the insert terminals 9 and 10 integrally formed with the case 8 as the main body of the apparatus via the projections 11 and 12 by the lead terminals 6 and 7, and is fixed on the heat dissipation base 2. Connected to unit 13.

The emitter terminal 3 has a collector terminal 4 and a base terminal 5
Similarly, the lead terminal 14 is welded and fixed to the insert terminal 15 through the projection 16 and connected to the board unit 13, and further connected to the heat dissipation base 2 through the ground lead 17 and the screw 18. .

Reference numeral 20 in FIG. 2 indicates an amplification / switching circuit, and an integrated full package type IC is used for this amplification / switching circuit 20. The amplification / switching circuit 20 is mounted on the substrate unit 13 together with the capacitor 21 and the resistor 22.

The resistor 23 in FIG. 1 is built in the case 8, and its terminals 23a and 23b are welded and fixed to the insert terminals 9 and 9a by ultrasonic welding or the like. The case 8 is filled with a silicon-based gel 25 that protects each component.

As shown in FIG. 3, the power transistor 1 has a semiconductor element 26 bonded to a lead frame 27 with solder 28, and has a diameter of 20 mm.
The semiconductor element 26 and the external connection lead 30 are ultrasonically welded with an aluminum wire 29 of 0 μ or 250 μ, and a varnish-based coating agent (JCR) 31 is applied to protect the surface of the semiconductor element 26, and the whole is molded and sealed. It is configured by being covered with resin 32.

The molding encapsulation resin 32 is selected based on (1) high thermal conductivity, (2) small heat shrinkage, and (3) good moldability and releasability, and specifically Is an epoxy mold resin. This epoxy mold resin
The coefficient of thermal expansion of 32 and the coefficient of thermal expansion of the varnish-based coating agent 31 are set to be close to each other.

Further, the molding and encapsulation techniques include (1) not deteriorating the heat dissipation characteristics, (2) making the heat dissipation characteristics uniform in the molding and encapsulating resin, (3) ensuring mechanical strength, and (4) ) It is necessary to ensure electrical insulation, and as a method of satisfying these, a sealing method using transfer molding, which is excellent in mass productivity, was adopted. As shown in FIGS. 4 and 5, the mold is a both-ends supporting type using an upper mold 35 for sealing and a lower mold 36 for sealing, and when molding the transistor 1,
By supporting both ends 27a and 27b of the lead frame 27, it is possible to precisely control the resin thickness.

In the ignition device configured as described above, the lead terminals 6, 7, 14 are attached as follows.

As shown in FIGS. 6 and 7, a plurality of lead terminals are initially arranged in parallel and are integrally provided on the lead frame 37. Then, as shown in FIG. 8, a plurality of board units 13 are arranged in parallel along the lead frame 37 and each lead terminal is printed at a predetermined connection position of each board unit 13 and a reflow soldering process. To be done. Further, at this time, the amplification / switching circuit 20, the capacitor 21, and the resistor 22 are reflow-soldered to the board unit 13. After that, as shown in FIGS. 9 and 10, the lead frame 37 is cut off together with unnecessary portions by a cut-off press (not shown). This allows the lead terminals 6, 7, 14 to be efficiently connected to the board unit 13
Connect to.

The entire ignition device is assembled as follows. 11th
As shown in the figure, the resistor 23 is inserted into the recess 40 formed in the one side 8a of the upper surface of the case 8 in which the insert terminals 9, 10, 15 are integrally molded, and as shown in FIG. 12 and FIG. The terminals 23a and 23b of the resistor 23 are spot-welded to the insert terminals 9 and 9a. As a result, the resistor 23 is built in the case 8.

On the heat dissipation base 2, as shown in FIGS. 14 and 15,
The substrate unit 13 to which the amplification switching circuit 20 and the lead terminals 6, 7, 14 and the like are attached is adhered to the power transistor 1.

When assembling the heat dissipation base 2 and the case 8, see FIG.
As shown in FIG. 18, so that the lead terminals 6, 7, 14 and the insert terminals 9, 10, 15 are not in contact with each other, the case 8 is slightly on the right side of the heat dissipation base 2 (see FIGS. 16 and 17). (The right side with respect to the plane of FIG. 2) so that they abut each other and then the left side, and the insert terminals 9, 10, 15 are also inserted under the upper ends of the lead terminals 6, 7, 14.

Then, when the heat dissipation base 2 and the case 8 are aligned with each other, the convex portion 42 formed on the case 8 is press-fitted into the groove portion 43 formed on the base 2 to be adhesively fixed.

After that, each lead terminal 6,7,14 and insert terminal 9,10,15
And are welded through the projections 11, 12, 16 formed on the insert terminals 9, 10, 15. Then, the silicon gel 25 is injected into the case 8 and the cover 45 is attached to complete the ignition device.

As described above, since the power transistor 1 is a full package type in which most of the lead frame 27 is covered with the epoxy type molding resin 32 having the characteristics of high thermal conductivity and low thermal expansion coefficient, the number of bonding parts is reduced. As a result, the airtightness of each bonding portion is significantly improved, and oxygen in the air does not enter the bonding portion. As a result, it is possible to prevent deterioration of the solder in the bonding portion.

Further, since the epoxy-based mold resin has a good thermal conductivity, the heat dissipation from the semiconductor element 26 to the outside is improved, and the thermal fatigue resistance of the bonding portion of the power transistor 1 is improved. This significantly improves the reliability of the ignition device.

Further, since the epoxy type mold resin 32 and the varnish type coating agent 31 have similar thermal expansion coefficients to each other, the aluminum wire 29 as a bonding wire will not be broken even when the temperature largely changes.

A plurality of lead terminals are arranged in parallel to form a lead frame.
Molded integrally with 37, many lead board units at once
As it can be connected to 13, it is easy to assemble.

The resistor 23 is built in the recess 40 of the case 8 and fixed by welding, and is not damaged by an external force, and the case 8 has good heat dissipation and the heat resistance of the connection portion of the resistor 23 is improved. Further, the ignition device can be downsized.

Effects of the Invention As described in detail above, according to the ignition device for an internal combustion engine of the present invention, since it is a full package type in which a plurality of parts are combined into one as much as possible, the number of bonding portions is reduced, and a failure due to deterioration of the bonding portions is prevented. It can be significantly reduced and the reliability of the device is greatly improved.

In addition, because the resistance is attached by welding in the main body of the device,
There is an advantage that damage due to external force is eliminated, heat resistance is improved, and the device can be downsized.

[Brief description of drawings]

FIG. 1 is a plan view showing an internal combustion engine ignition device of the present invention, FIG. 2 is a partially cutaway side view of the internal combustion engine ignition device shown in FIG. 1, and FIG. 3 shows a power transistor according to the present invention. Side sectional view, FIG. 4 is a side sectional view showing a mold for molding a power transistor according to the present invention, FIG. 5 is a plan view showing a power transistor according to the present invention, and FIG. 6 is a plurality of lead terminals arranged in parallel. FIG. 7 is a plan view showing a lead frame integrally connected to the lead frame, FIG. 7 is a side view showing the lead frame shown in FIG. 6, and FIG. 8 is a plan view showing a plurality of board units arranged along the lead frame. FIG. 9 is a plan view showing a state where the lead frame is cut off from the state of the lead frame and the substrate unit shown in FIG. 8, FIG. 10 is a side view showing the unit shown in FIG. 9, and FIG. 11 is the present invention. Perspective view showing the case of the ignition device of FIG. 12 is a plan view of the case shown in FIG. 11, FIG. 13 is a front view of FIG. 12, FIG. 14 is a plan view showing a heat dissipation board of the point device of the present invention, and FIG. 15 is shown in FIG. Front view of the heat dissipation board of the ignition device shown, FIG. 16 is a plan view showing the ignition device of the present invention, FIG. 17 is a front view of the ignition device shown in FIG.
18 is a right side view of the ignition device shown in FIG. 16, FIG. 19 is a plan view showing a conventional internal combustion engine ignition device, and FIG. 20 is a front view of the ignition device shown in FIG. 1 …… Power transistor, 6,7,14 …… Lead terminal, 8
…… Case, 13 …… Board unit, 20 …… Amplification / switching circuit, 23 …… Resistance, 37 …… Lead frame.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Kanazawa 4-3-1, Tsunashima-higashi, Kohoku-ku, Yokohama-shi, Kanagawa Matsushita Communication Industrial Co., Ltd. (56) Reference JP-A-58-199521 (JP, A) JP-A-61-137111 (JP, A) JP-A-61-43460 (JP, A) Real-open Sho-62-29473 (JP, U) Actual-open Sho-56-96656 (JP, U) Actual-open Sho-61-142460 (JP, U)

Claims (2)

[Claims] 1. A lead frame in which a plurality of lead terminals each having a step formed by bending are integrally connected, and the lead terminals connected to the lead frame and an amplification / switching circuit are built in and integrated. Board on which the full package type IC is fixed, a heat dissipation base on which the boards divided by cutting the lead frame are mounted, and combined with this heat dissipation base, the lead frame is cut into individual pieces. A case having an insert terminal to which the divided lead terminal is fixed, and a power transistor which protects the surface of the built-in element with a coating material and is fully packaged with an epoxy resin having a thermal expansion coefficient substantially equal to that of the coating material. An internal combustion engine ignition device provided. 2. The ignition device for an internal combustion engine according to claim 1, wherein a resistance is housed in a case having an insert terminal, and the resistance and the insert terminal are fixed by welding.