JP2001230334A - Electronic component unit for automobiles and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed structure type electronic component or electronic control product for vehicle mount use which facilitates mounting its frame, etc. SOLUTION: In the electronic component unit for automobiles which has a cap hermetically sealed with a base mounting a circuit board having mounted bare chips, the base has ears for mounting the frame, the cap has a flange having a smaller thickness than the thickness of the cap, and the base and the flange are fusion-bonded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component unit for an automobile and a method of manufacturing the same.

[0002]

2. Description of the Related Art An electronic component unit for an automobile has a structure in which a bare chip is mounted on a substrate and hermetically sealed by adopting a high performance control circuit mounted therein and downsizing the electronic component unit itself. I have. Automotive parts are used in severe environments such as temperature and humidity, and electronic parts are required to have high airtightness. Therefore, it is disclosed in a laser process technology handbook that the hermetic sealing with glass is performed by laser welding. Japanese Patent Application Laid-Open No. 10-32276 discloses that a weld metal portion and a flange portion of a metal cap are pressurized in order to prevent weld splash from entering the cavity.
There is a disclosure of a packaging method for a power semiconductor device in which metal hermetic sealing is performed by electric resistance welding.

Japanese Patent Application Laid-Open No. 5-26758 discloses a pressure sensor in which a lower flange portion of a cap welded to an outer peripheral step portion of a metal outer ring of a pressure sensor is formed to be thinner than other portions of the cap. There is a disclosure method for improving the detection accuracy of the image.

[0004]

However, the above-mentioned prior art does not disclose mounting components on a housing or the like, and requires another mounting structure to function as a control component of an automobile.

An object of the present invention is to provide a mounting structure with a base which is sealed in advance so that the housing or the like can be easily mounted,
It is an object of the present invention to provide an electronic component unit which simplifies an assembling process of an in-vehicle product including a control component or an electronic component unit and realizes a reduction in the total size of the in-vehicle product, and a method of manufacturing the same.

[0006]

The above object can be achieved by the following means. The gist of the invention is as follows: (1) In an automotive electronic component unit in which a base on which a circuit board on which a bare chip is mounted is mounted and a cap are hermetically sealed, ears for mounting a housing are provided on the base. The cap has a flange, and the thickness of the flange is smaller than the thickness of the cap, and is an electronic component unit for an automobile in which the base and the flange are melt-bonded.

In the above, the thickness of the flange is 0.3 to
1 mm, and it is preferable that the penetration depth of the fusion joint between the base and the flange is 0.3 to 0.7 mm larger than the thickness of the flange.

The base and the cap may be made of a plated cold-rolled steel plate or an iron-based alloy, and the hermetically sealed portion may be made of glass, or the base and the cap may be made of a material. Is an aluminum alloy, and the hermetically sealed portion is preferably a cured resin.

It is preferable that a brazing filler metal is inserted at an interface between the base and the fusion joint of the flange.

The electronic component unit for a vehicle according to the present invention can be used as a controller installed in an automatic transmission unit or a control unit for a vehicle-mounted radar.

(2) In a method of manufacturing an electronic component unit for an automobile in which a base and a cap on which a circuit board on which a bare chip is mounted are mounted are hermetically sealed, ears for mounting a housing are formed on the base. Step, the cap has a flange, the thickness of the flange portion is 0.3 to 1 mm,
Manufacturing of an electronic component unit for an automobile, comprising a step of melting and joining the cap and the base by laser welding and joining such that the penetration depth of the joint is 0.3 to 0.7 mm larger than the flange thickness. Is the way.

The present invention is achieved by providing an ear plate portion serving as a housing attachment portion on a base on which a circuit board is mounted. In this case, since the base with the ear plate can be integrally formed, the number of parts can be reduced and the product itself can be mounted in a narrow space.

In addition, it is possible to mount electronic control components in a place where it could not be installed conventionally, for example, to directly attach to a transmission section or to install a transmission in a transmission. However,
At this time, the welding method becomes important. From the viewpoint of product miniaturization, it is necessary to reduce the area of the base itself and also reduce the joint portion with the cap to be welded. If the earplate does not exist, it is possible to place a cap with the same external dimensions as the base on the base and weld it from the side, etc., but it is impossible to weld from the side at the earplate. Yes, the welding method is restricted, and welding from above the cap is required.

When welding is performed from the cap side, it is necessary to use a long focal length lens system so that the side wall of the cap does not interfere with the beam in the case of laser welding, for example. In order to obtain highly reliable sealing by laser welding, it is important to control the penetration depth during welding and to secure the butt joint accuracy.

Normally, the thickness of the base is thicker than the cap and is in the range of 1 to 3 mm, and the thickness of the cap is 0.5
範 囲 1 mm. From the viewpoint of welding, the thinner the thickness of the welded portion of the cap, the smaller the input energy at the time of welding. Therefore, it is desirable to have a cap structure in which the welded portion of the cap, that is, the peripheral flange portion is partially thinned. However, in the case of a structure in which the flange is partially thinned, the flatness of the flange deteriorates as the thickness becomes thinner, and the gap when the flange is abutted increases. It is desirable to do.

[0016] However, the gap at the time of the butting engineering is zero.
Therefore, it is necessary to ensure sufficient penetration into the base side.

As a result of studying various welding conditions, the inventors found that the thickness of the welded portion of the cap was 0.3 mm to 0.7 mm.
It was found that stable sealing welding without solidification cracking at the time of welding can be achieved by controlling the penetration depth to which the value of (1) is added.

In this case, the definition of the penetration depth is, for example, when there is a gap between the base and the cap, the sum of the thickness of the cap welding portion and the penetration depth of the gap and the base portion. When the penetration depth of the welded portion is smaller than the above 0.3 mm, the cross-sectional shape of the fused portion becomes concave on the surface, which causes an increase in tensile stress at the time of solidification shrinkage, thereby causing cracking. Conversely, if the penetration is greater than 0.7 mm, a large heat input is given to the base, resulting in an increase in the temperature of the bare chip mounted on the substrate on the base, which causes damage. .

If the penetration is controlled within the range of 0.3 to 0.7 mm, even if there is a gap of 50% of the thickness of the cap brim, the shape of the surface of the welded portion does not become concave,
Solidification cracking can be prevented. As described above, the penetration depth when there is a gap between the cap brim portion and the base is the sum of the brim thickness, the gap and the penetration amount of the base, so that the penetration of the base portion decreases as the gap increases It will be.

In the case of using a glass herme, an iron-based material is usually used in order to insert the glass at a temperature of about 1000 ° C. and to match the coefficient of thermal expansion with the glass. Can be made of an Al-based material. Al-based materials have better thermal conductivity and are therefore desirable from the viewpoint of heat radiation of the substrate mounted on the base. Furthermore, if an Al-based material is used, the weight of the electronic component itself can be reduced. Generally, welding of Al-based materials
Larger heat input is required than iron-based materials. This is Al
This is because a large amount of energy is required to melt the oxide existing on the surface. In the case of Al welding, the control of the penetration amount is not different from that of the iron-based material.

In order to achieve sealing with a relatively small laser power, a method may be adopted in which a brazing material is inserted between the cap and the base and melted. If the cap is formed using a commercially available Al material that has been previously coated with a brazing material, the process of inserting the brazing material during welding can be simplified. In this case, it is also possible to perform sealing by melting the brazing material and the cap and the base sandwiching the brazing material to a minimum, thereby further expanding the optimum welding range.

Hereinafter, the present invention will be described by way of examples.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

[0024]

Embodiment 1 FIG. 1 shows the structure of an electronic component having a welding structure according to the present invention. The base 1 having the ear plate portion of the attachment portion and the cap 2 having the flange portion are circumferentially welded to achieve sealing. The size of the ear plate is 10 mm x 20 mm,
The thickness is the same as the base. Figure 1 shows the cross-sectional structure of the weld
Shown below. Base thickness 2mm, cap 0.6
The thickness of the flange is 0.4 mm.
mm. The base and cap are made of SPCC, and the surface is plated with Ni. Note that a ceramic substrate 4 on which a bare chip or the like is mounted is mounted on the base.

FIG. 2 shows the state of welding. The welding was performed using a YAG laser, and a laser beam 5 was applied to the cap from a vertical direction slightly inside the end of the cap. The cross-sectional shape of the melted portion was convex, and the laser irradiation position was adjusted so that the end portion was completely melted. At this time, the gap between the cap and the base is 0.2 mm at maximum, and the total penetration depth is 0.8 mm, which is 0.4 mm larger than the cap thickness.
mm. As a result of performing a leak test after welding and examining the state of sealing, the leak amount was 0.

[0026]

Embodiment 2 FIG. 3 is an enlarged view of a welded portion. By varying the cap brim thickness a, the base penetration depth b, and the gap c between the cap and the base, solidification cracking during welding and a leak state after sealing were examined. The overall penetration depth is the sum of a, b, and c. Table 1 shows the results. Cap, base material,
The laser irradiation method is the same as in the first embodiment. In the range where the penetration depth was added to the value of a by 0.3 to 0.7 mm, there was no solidification cracking or leakage. When the penetration increased further, there was no leakage, but an abnormality sometimes occurred in the substrate circuit. When the penetration was smaller than that, solidification cracking and leakage occurred.

[0027]

[Table 1]

[0028]

[Embodiment 3] The laser irradiation angle in Embodiment 1 was set to 4
Welded at an angle of 5 degrees. The amount of penetration c of the base was almost the same as that in the case of vertical, and there was no solidification cracking or leakage.

[0029]

[Embodiment 4] The cap and base materials of Embodiment 1 were changed to Al.
We changed the material and welded the base with plastic harme. By making the laser power larger than SPCC,
The same penetration as in Example 1 was obtained, and it was confirmed that there was no solidification crack or leak in the Al material.

[0030]

Embodiment 5 Al with plastic herme applied to the base
Al with brazing material coated on the cap
The material was molded and sealed and welded. Laser light oblique 45
Irradiation was performed to melt the brazing material and the base and the cap sandwiching the brazing material.

FIG. 4 shows a cross section of the welded portion at this time. The base and cap were sealed with brazing material, and no leak was detected.

[0032]

According to the present invention, the ear plate can be easily mounted on the housing by installing the ear plate on the base, and the weld solidification cracking can be achieved by controlling the appropriate welded structure and the amount of penetration during welding. And a highly reliable sealing structure can be obtained.
In particular, it is possible to supply electronic components and electronic control products that can be mounted on products with limited installation space in harsh environments such as automobiles.

[Brief description of the drawings]

FIG. 1 shows an outline of the appearance of an electronic component unit and a cross section of a welded portion.

FIG. 2 is a sectional view of a welding method and a welded portion.

FIG. 3 is an enlarged sectional view of a welded portion.

FIG. 4 is a sectional view of a welded portion when a brazing material is used.

[Explanation of symbols]

1 ... base with earplate 2 ... cap with brim 3
… Welding and melting part, 4.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shin Onose, 2520 Oita Takaba, Hitachinaka City, Ibaraki Prefecture Inside the Hitachi, Ltd. Automobile Equipment Group (72) Inventor Koji Harada 2520 Address Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi, Ltd. Automotive Equipment Group

Claims (8)

[Claims] 1. An electronic component unit for an automobile, wherein a base on which a circuit board on which a bare chip is mounted is mounted and a cap are hermetically sealed, wherein the base is provided with ears for mounting a housing. Has a flange, the thickness of the flange is smaller than the thickness of the cap, and the base and the flange are melt-bonded. 2. The method according to claim 1, wherein the thickness of the flange is equal to 0.1.
3 to 1 mm, and the penetration depth of the fusion joint between the base and the flange is 0.3 to 0.7 m greater than the thickness of the flange.
An electronic component unit for a vehicle, wherein the electronic component unit is larger by m. 3. The material according to claim 1, wherein the base and the cap are made of a plated cold-rolled steel plate or an iron-based alloy, and the hermetically sealed portion comprises glass. Automotive electronic parts unit. 4. The electronic component unit for an automobile according to claim 1, wherein a material of the base and the cap is an aluminum alloy, and the hermetically sealed portion is a cured resin. 5. The electronic component unit for an automobile according to claim 1, wherein a brazing filler metal is inserted into an interface between the base and the flange. 6. A controller, wherein the electronic component unit for a vehicle according to claim 1 is installed in an automatic transmission unit. 7. An electronic component unit for an automobile according to claim 1, wherein the electronic component unit for an automobile is a control unit of an on-vehicle radar. 8. A method for manufacturing an electronic component unit for an automobile, wherein a base and a cap on which a circuit board on which a bare chip is mounted are mounted are hermetically sealed, a step of forming an ear for mounting a housing on the base. The cap has a flange, the thickness of the flange is 0.3 to 1 mm, and the cap and the base are fusion-bonded by laser welding; More than 0.3
A method for manufacturing an electronic component unit for a vehicle, comprising a step of joining the electronic component unit so as to increase the size by 0.7 mm.