JP2011003682A - On-vehicle electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem wherein, when a condensation seal is used for a seal material of a base and a cover of an on-vehicle electronic apparatus, hardening thereof is slow and productivity is degraded.SOLUTION: This on-vehicle electronic apparatus includes a base for dissipating heat from an electronic component and installing a circuit board thereon. The on-vehicle electronic apparatus for installing, on the base, a board for forming the circuit board by mounting the electronic component thereon is structured such that, in a seal surface of the base and the cover, a through-hole is formed on the cover, and a seal material runs off therefrom.

Description

  The present invention relates to an internal combustion engine, particularly an automobile engine control unit, and a sealing structure for a base and a cover of a sensor mounted in an engine room.

  Conventionally, a substrate is mounted on a base and a cover is bonded to the entire periphery, or a substrate is stored in a housing and a seal structure is bonded to the cover. Japanese Patent Laid-Open No. 2002-216886 is an example in which the above general structure is presented.

JP 2002-216886 A

  However, in the case of the structure having the same structure as the above-mentioned Patent Document 1 and a waterproof seal using a normal temperature curing condensation-cured silicone sealant that cures from paste to rubber by chemically reacting with the moisture in the air in the sealant Since only the both ends of the base and cover are in contact with air and moisture can be supplied only from these ends, the seal material is cured from the surface and completely cured to the inside. Is a factor that deteriorates productivity because a lot of time is required.

  Therefore, an addition-reactive silicone adhesive that cures to rubber rather than paste by heat-curing the sealing material is often used. The heat-cured silicone sealant is a good sealant with high adhesion reliability, but the heat-cured silicone sealant has a drawback that it does not cure unless it is exposed to a temperature environment of at least 100 ° C. or higher. (In the case of a one-component type) If a part that cannot be heated is mounted on a circuit board for some electronic parts, a heat-curing seal cannot be used. There are many electronic devices used.

  Here, the point of discussion is returned to the condensation type silicone sealant.

  Condensation-type silicone-based sealing materials may also be a weak point that their adhesive strength is smaller than that of heat-cured seals, other than the productivity described above.

  Furthermore, in view of the environment where on-vehicle electronic devices currently distributed in the market are placed, it is considered that water and salt water are less likely to be dripped and exposed to a shower. As an example, the cover of many engine control units employs a plated steel plate plated on the surface of iron, and eventually becomes corroded. The same applies to aluminum that is frequently used for the base. Especially in the case of salt water, aluminum does not have much resistance.

  From the viewpoint of corrosion, corrosion tends to occur from the edges. In the case of the engine control unit presented as a previous example, the corner edge portion of the outer peripheral end portion of the cover and the corner edge portion of aluminum similarly serve as a base point for corrosion.

  The present invention provides a solution to the above-mentioned problems by providing a structure that improves the curing rate of the sealing material and improves the productivity without using new parts or special sealing materials, and the application shape of the sealing material. The purpose is to present measures to improve the water resistance and saltwater corrosion resistance while improving the seal strength.

  In order to achieve the above object, in the sealing portion between the cover and the base or the board or the connector according to claim 1, the cover is provided with a through hole, and at least the sealing material protrudes in a convex shape from the through hole. It is characterized by having a seal cross-sectional shape.

  As described above, the adhesive structure in which the sealing material protrudes from the through-hole provided in the cover has a contact area with moisture-containing air, particularly in the case of a room temperature curing silicone-based sealing material in which the sealing material is cured by a condensation reaction. By increasing the temperature, the curing rate of the room temperature curing sealing material becomes faster, and it becomes possible to improve productivity.

  Further, in the above, the through-hole is provided in the cover, and the seal material protrudes in a convex shape, and the adhesive cross-sectional shape is obtained by spreading from the outer periphery of the through-hole due to the fluidity of the seal material or external force. By forming a shape like a rivet, the adhesion strength of the seal is improved due to an increase in the bonding area and a locking effect due to the rivet shape.

  Furthermore, according to the above-mentioned adhesive structure, the water and salt water adhering to the cover have a convex shape due to the sealing material formed on the cover surface, so that the balance of the surface tension of water droplets and salt water itself deteriorates. By being in a state where it is difficult to stay on the cover, water drops and salt water are likely to drop outside. Furthermore, when the sealing material is silicone, the water repellency of the silicone polymer is also helped, so water droplets and salt water are less likely to stay on the cover surface and drop outside. Adhesion reliability at the seal interface is improved.

  In the seal structure according to claim 6, since the base point of corrosion due to moisture or salt water is generated near the interface with the seal material on the outer periphery of the cover, the seal material is overhanging from the outer periphery of the seal portion of the base and the cover. The seal structure may be integrated from the outer peripheral surface of the cover to the inner periphery.

  According to the present invention, a measure for solving the above problems is to provide a structure that improves the curing speed of the sealing material and improves the productivity without using new parts or special sealing materials, and the application shape of the sealing material. This can be a measure to improve the water resistance and salt water corrosion resistance as well as improving the seal strength.

FIG. 3 is a cross-sectional structure diagram of a general on-vehicle electronic device currently in circulation. The top view of the general vehicle-mounted electronic device currently distribute | circulating. The cross-section figure of the vehicle-mounted electronic device by this invention. The top view of the vehicle-mounted electronic device by this invention. FIG. 4 is a diagram showing a seal structure of a general on-vehicle electronic device currently in circulation, a relationship between a curing time of the seal material and a part of the seal material. FIG. 4 is a diagram illustrating a relationship between a sealing structure of an in-vehicle electronic device according to the present invention, a curing time of the sealing material, and a portion of the sealing material. 2 is a cross-sectional view of a seal structure of a seal structure according to the present invention. 2 is a cross-sectional view of a seal structure of a seal structure according to the present invention. 2 is a cross-sectional view of a seal structure of a seal structure according to the present invention. A state in which water droplets are attached to general in-vehicle electronic devices that are currently distributed. The energy balance state of water droplets when water droplets adhere to the general in-vehicle electronic devices currently in circulation. A state in which water droplets adhere to the in-vehicle electronic device according to the present invention. The state diagram when a water droplet adheres to the vehicle-mounted electronic device by this invention. The cross-section figure of another Example of the vehicle-mounted electronic device by this invention. The top view of another Example of the vehicle-mounted electronic device by this invention.

  A number of through holes are provided in the cover at the bonding site between the cover and the base, or the board and the connector, and the sealing material is more convex than the through hole, and the sealing material is wet and wider than the outer periphery of the through hole. In this manner, it is achieved by forming a seal cross section in which the seal cross section has a rivet shape.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The present invention will be described using an example in which the seal structure is applied to the seal structure of an in-vehicle electronic device. Particularly, the seal structure of the present invention is suitable for a seal structure of an electronic device disposed in an engine room of a vehicle, such as an engine control unit, a sensor, a hybrid module, an inverter, a motor, and an actuator.

  Before describing the seal structure of the present invention, the present invention will be described after the product structure is described using typical examples of in-vehicle electronic devices currently used in many vehicles.

  The vehicle electronic device is roughly divided into a base 1, a substrate 2, a cover 3 serving as a housing, and a connector 4. In the present invention, the cover 3 is directly sealed to the base 1 with the sealing material 5 in the present invention. However, the case and the connector are fixed to the base with the sealing material, and the upper surface is covered with the cover. Clarify that the generic structure of electronic equipment is included.

  FIG. 1 is a cross-sectional view of an in-vehicle electronic device used in many vehicles, here, an engine control unit, and FIG. 2 is a plan view thereof.

  Reference numeral 1 denotes a base that also serves as a heat sink for housing the substrate 2 and a heat radiating body for the electronic component 7, and many are formed by die casting or pressing with aluminum. Recently, there is a tendency to use a high heat dissipation material in order to emphasize heat dissipation. The end of the base 1 is provided with a hole for fixing the product to the vehicle, and is fixed to the vehicle by screwing. Reference numeral 2 denotes a substrate. The circuit substrate is a printed circuit board on which a circuit conductor is formed, or an electronic component 7 such as an integrated circuit, a capacitor, a chip resistor, or a coil is electrically connected to the surface of the ceramic substrate by wire bonding, solder, or a conductive adhesive. It becomes a circuit board by being fixed while ensuring the electrical conduction. Then, the substrate is fixed to the base 1 with screws 6, adhesion, less fit and the like.

  The connector 4 is mounted on the base 1 and connected to the substrate 2 with solder, conductive adhesive or the like, so that circuit input / output functions. There is also a step of storing the connector 4 in the base 1 after first being fixedly connected to the substrate 2.

  And the sealing material 5 is apply | coated to the predetermined | prescribed site | part of the base 1 and the connector 4, the cover 3 is mounted | worn, and it hardens, and a vehicle-mounted electronic device is completed.

  The sealing material 5 seals an aluminum die casting often used for the base 1 and a plated steel plate often used for the cover 3. In the connector 4 portion, the resin forming the base 1 and the connector 4 (nylon, PBT: polybutylene terephthalate, etc.) is sealed, and on the other side, the connector 4 resin and the cover 3 are sealed. In order to seal different members, it is preferable to use a viscoelastic sealing material, and in many cases, a silicone-based sealing material is used. The cover 3 is often a hot dip galvanized steel plate.

  At present, as described above, the sealing material 5 for sealing the base 1, the cover 3, and the connector 4 is often a silicone-based sealing material as a viscoelastic adhesive from the viewpoint of thermal stress relaxation. Silicone sealing materials are roughly classified into two types having two types of curing functions. One is a condensation type that reacts with moisture (humidity) in the atmosphere and cures from the surface that reacts with moisture, and the other is an addition type in which the sealing material is cured by heating. Electronic devices that have a control circuit such as an engine control unit are often equipped with components such as capacitors that shorten their life when high temperatures are applied. Condensation that cures at room temperature rather than heat-curing silicone sealants In recent years, the structure using the type of sealing material 5 tends to increase.

  However, a problem when using the condensation type silicone sealant 5 is that the curing time is slow and the productivity is deteriorated. Condensation type silicone sealant is a mechanism in which moisture (humidity) in the air and silanol groups blended in the silicone resin are hydrolyzed to form a crosslink and rubberize (harden) from the paste. Since only the portion intervening with moisture can be cured, there is a drawback that curing takes a long time because curing starts from the surface in contact with moisture and progresses in the depth direction from the moisture contact surface.

  As can be seen from the cross-sectional structure diagram of the electronic device in FIG. 1, many of the electronic devices currently on the market are in contact with moisture because of the structure in which the seal material 5 is applied to the outer periphery of the base 1 and covered with the cover 3. These are only the outer peripheral end of the base 1, the exposed portion of the sealing material 3 of the cover 3, and the opposite end of the seal. When the seal application width is long, the curing time becomes longer in accordance with the width. It has been confirmed by experiments that a standing time of at least one day is required for the sealing material 5 to be completely cured. On the other hand, the heat-curing silicone-based sealing material cures when left at a predetermined temperature for 30 to 60 minutes, so that the heat-curing sealing material is clearly superior in productivity.

  However, the heat curing type silicone sealant is optimal for placing and sealing the circuit board on which the electronic parts that cannot be heated are mounted on the base 1 and the cover 3 as the condensation type silicone sealant. However, it is still used in many electronic devices as the sealing material 5 because it has a superior advantage that compensates for the disadvantages of productivity such as being suitable for sealing large parts that do not enter the curing furnace.

  The present invention improves the disadvantage of poor productivity by devising the cover shape and speeding up the curing speed with respect to the point that the curing speed is slow and the productivity is deteriorated, which is a disadvantage of the condensation type sealing material. It is.

  The structure of the electronic apparatus according to the present invention will be described with reference to FIGS. FIG. 3 is a sectional structural view of an electronic apparatus according to the present invention, and FIG. 4 is a plan view thereof. After the board 2 on which the electronic component 7 is mounted on the base 1 is fixed with screws 6 and the connector 4 is connected to the circuit by electrical connection, the sealing material 5 is applied to the outer periphery of the base 1 and the cover 3 is entirely covered and cured. There is no change in the structure to be used, and the sealing material 5 is not a special product. The present invention is characterized in that a number of through holes 8 are provided in a portion of the cover 3 where a seal is applied, and the seal material 5 protrudes from the through holes 8 when the cover 3 is attached.

  The purpose and effect of providing the through hole will be described with reference to FIGS. FIG. 5 is a diagram showing the relationship between the bonding structure of the base 1 and the cover 3 of the electronic device currently on the market and the curing speed, and FIG. 6 is the bonding structure of the base 1 and the cover 3 of the electronic device according to the present invention and the curing. It is a relationship diagram of speed. In FIG. 5, only the end portion 10 of the seal sandwiched between the base 1 and the cover 3 is necessary for supplying the moisture 9 necessary for curing the sealing material 5 of the electronic equipment currently distributed. Therefore, the sealing material 5 is cured from both end portions 10 of the sealing material and is cured toward the inside. Therefore, taking the time to cure on the vertical axis and the seal position (width) on the horizontal axis, the relationship between the cure time and the seal part shows that the center part requires the most time for curing.

  In the present invention, the through-hole 8 provided in the cover 3 can absorb moisture from the exposed portion of the sealing material 5 that protrudes from the through-hole 8, and the water-receiving area that can receive moisture increases. Thus, the curing rate is dramatically improved by being able to give moisture to the inside which is hard to cure.

  As a result of the inventor's confirmation, in the case of an electronic device distributed in the market shown in FIG. 5, the time until the complete curing is set as To, and the time until the complete effect is obtained in the electronic device having the structure shown in FIG. Assuming T1, the relationship between the two confirmed that T1 = 1 / 2To and an effect that can halve the curing time.

  7, 8, and 9 are cross-sectional views of a portion of the sealing material showing how the sealing material 5 protrudes from the cover 3 provided with the through holes 8. FIG. 7 shows a recommended seal structure. As the sealing material 5, a paste having a semi-fluid type rheology that is not high in thixotropy is suitable. After the sealing material 5 is applied to the base 1, the sealing material 5 is covered with the cover 3. If left in that state, the protruding sealing material wets and spreads to a state larger than the outer periphery of the through hole due to surface tension. By curing in this state, the seal cross-section becomes a rivet shape, and the adhesive strength of the seal can be increased, so that the adhesive reliability can be improved at the same time, and the highly reliable electronic Equipment can be provided. The seal structure shown in FIG. 8 can also increase the curing speed and improve the productivity, but it is difficult to intentionally form this shape. If the structure shown in FIG. 9 is also intended, it can be manufactured, but the amount of dent varies and management is difficult. In reality, it has been confirmed that the seal structure shown in FIG. 7 has the least variation and good shape stability.

  Further, it will be explained that the present invention also exhibits the effect of improving the reliability against the corrosiveness. In-vehicle electronic devices are required to have various functions due to recent digitization, and on the contrary, the part where the engine control unit is mounted is increasingly installed in the engine room. The engine room is in an environment where ionic solutions such as water, muddy water, and salt water are exposed to showers, direct sprays, and water splashes, but most of the materials used for the base 1 of electronic equipment are aluminum die castings and covers. Most of the materials used are plated steel plate presses, which become the starting point of corrosion when ionic aqueous solutions such as water, muddy water, and salt water adhere. In particular, when the water droplets shown in FIG. 11 adhere to the metal flat plate, the water droplets 11 attached to the metal surface become a ball shape with the internal energy of the water droplets, that is, the surface tension 12, and the surface of the cover 3 in a stable state. Exists. Moreover, since the surface of the cover 3 is plated, the surface has micro undulations and is in a surface state where water droplets are easily attached. Moreover, the corner part of the outer periphery of the cover 3 is also an edge part, and the water droplet 11 adheres and tends to stay in a stable state. When the staying water droplet is an ionic aqueous solution such as salt water, ions are concentrated to form a concentration cell and serve as a base point for corroding aluminum or plated steel sheet.

  The sealing structure of the present invention is a structure in which the through hole 8 is provided in the cover 3 and the sealing material 5 is covered so that the sealing material 5 protrudes from the through hole 8. According to the present invention, when the water droplet 11 adheres to the surface of the cover 3, the water droplet 11 originally wants to be a droplet with the most stable energy, but because of the unevenness on the cover surface, the shape of the water droplet in an irregular state It becomes. The water droplets in this distorted state generate a field that is unbalanced in the surface tension inside the water droplets and are in an unstable energy state, so that they cannot stay in the same part of the cover 3 and cover More drops. In the case where the seal protruding from the cover 3 is the silicone-based sealing material 5, the water-repellent effect of repelling the water droplets 11 having the water repellency possessed by dimethylpolysiloxane or methylphenylpolysiloxane serving as the silicone polymer is a water droplet. Even if it adheres to the outer periphery of the cover 3, which is most likely to adhere to the cover 3, it drops off to the outside due to the water repellent effect of the silicone polymer, and an aqueous solution that becomes a corrosion medium may stay in the cover 3. Therefore, reliability against corrosion can be improved.

  The structure in which the sealing material 5 that makes it difficult for the water droplets 11 of the present invention to stay in the cover 3 protrudes from the cover 3 and the silicone-based sealing material is used for the sealing material 5, thereby breaking the balance of the surface tension of the water droplets, and It is the most efficient structure that can use the water-repellent effect of silicone polymer in combination, and exhibits the effect of improving the reliability against corrosion caused by ionic solutions such as water, muddy water, and salt water.

  In the present invention, the through hole 8 is provided in the adhesion portion of the outer peripheral portion of the cover 3 and the sealing material 5 protrudes, but it may be formed on the entire cover 3. However, providing the through-hole 8 at the center of the cover 3 is structurally meaningless and it is applied to the flat portion of the cover 3 in a dot shape with a dispenser. However, this method takes man-hours and, as described above, the center of the cover is rarely the starting point of corrosion, and it has been confirmed from experiments that it is not very effective.

  Another embodiment of the present invention will be described with reference to FIGS. FIG. 14 is a cross-sectional structural view showing an embodiment of the present invention, and FIG. 15 is a cross-sectional structure of a seal portion which is the gist of the present invention.

  In Example 1, an ionic solution such as water, muddy water, and salt water is in an environment where it is exposed to a shower, direct spray, or water spray, but most of the materials used for the base 1 of the electronic device are aluminum die castings and covers. Most of the materials used were plated steel plate presses, and it was explained that when an ionic aqueous solution such as water, muddy water, or salt water adheres, it becomes a starting point of corrosion. In this embodiment, the cover 3 and the entire outer peripheral portion of the base 1 serving as a base point of corrosion are covered with a sealing material 5. A sealing material is applied to the end of the base 1 and covered with a cover 3. And it is the structure which apply | coats a sealing material to a cover edge part whole periphery. As shown in FIG. 15, the sealing structure of the sealing material is such that the base 1 and the cover 3 are sealed, and the end of the cover 3 is overhanged and integrated to reach the end of the cover 3, thereby By completely covering the end portion of the cover with the sealing material 5, a structure in which water droplets do not come into contact with the end portion of the cover 3 is obtained, and the reliability against corrosion is improved.

  The present invention is suitable for a seal structure of an engine control unit, a sensor, a hybrid module, an inverter, a motor, and an actuator, which are on-vehicle electronic devices.

  Furthermore, in addition to automobiles, it is also suitable for sealing structures for industrial equipment and plant electronic equipment, including agricultural machinery and generators.

1 Base 2 Board 3 Cover 4 Connector 5 Sealing material 6 Screw 7 Electronic component (Integrated circuit, capacitor, chip resistor, coil, inductance, etc.)
8 Through-hole 9 Moisture 11 Water drop 12 Surface tension

Claims (8)

It is an in-vehicle electronic device that has a base for installing heat dissipation and circuit boards from electronic components,
By mounting electronic components, a substrate for forming a circuit board is installed on the base,
A connector that is an input / output interface of a circuit is installed on the base and is electrically connected to a circuit board,
In the in-vehicle electronic device having a structure in which the cover covering the circuit board is sealed by the aluminum base or the substrate, the connector portion and a sealing material having an adhesive functional group,
In the part where the cover and the aluminum base or the substrate and the connector part are sealed with a sealant, the cover and the base seal part are provided with a number of through holes in the cover of the seal part, and the adhesion An in-vehicle electronic device characterized in that the agent protrudes from the through hole. In claim 1,
An in-vehicle electronic device characterized in that a sealing material protruding from a through hole becomes a convex shape and wets and spreads around the through hole of the cover, thereby forming a rivet-like seal cross section. In claim 1,
The in-vehicle electronic device characterized in that the sealing material protruding from the through hole has a flat or concave bonding cross section on the upper surface of the cover. In claim 1,
In particular, the sealing material that seals the cover and the aluminum base or the substrate and the connector part is a silicone-based sealing material that undergoes a condensation reaction that forms a rubber from a paste state by a hydrolysis reaction with moisture in the air. In-vehicle electronic equipment. In claim 1,
The in-vehicle electronic device characterized in that the sealing material for sealing the cover and the aluminum base or the substrate and the connector is a viscoelastic body. In claim 1,
The on-vehicle electronic device is characterized in that the through-hole provided in the cover is circular, elliptical or polygonal. In claim 1,
An in-vehicle electronic device characterized in that the sealing material that protrudes from the cover is formed not only on the bonding site but also on the entire cover. It is an in-vehicle electronic device that has a base for installing heat dissipation and circuit boards from electronic components,
By mounting electronic components, a substrate for forming a circuit board is installed on the base,
A connector that is an input / output interface of a circuit is installed on the base and is electrically connected to a circuit board,
In the in-vehicle electronic device having a structure in which the cover covering the circuit board is sealed with the aluminum base or the board, the connector portion and the sealing material,
In the part where the cover and the aluminum base or the substrate and the connector part are sealed with a sealing material, the bonding surface of the base or the board and the connector part overhangs from the end part and covers the entire end part of the cover. In-vehicle electronic equipment that has a covering structure.

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