JP5645693B2 - Air flow measurement device - Google Patents

Description

  The present invention relates to an air flow rate measuring device, and more particularly to an air flow rate measuring device arranged in an internal combustion engine of an automobile.

  Automobiles using an electronically controlled fuel injection system have become commonplace, and in recent years, further improvements in performance and functionality have been made, and sensors and control devices arranged in the engine room are increasing. For this reason, the wire harness which mutually connects these sensors and control apparatuses also becomes complicated.

  Against this background, it is desirable to reduce the number of parts and improve the scenery inside the engine room by integrating a plurality of sensors and control devices. For example, a measure to integrate a flow rate measuring device, a temperature detection device, and a humidity detection device and to share a connector is an example. This makes it possible to reduce the number of steps for assembling parts to the vehicle and simplify the wire harness. .

  As a method for forming such a structure in which a flow rate measuring device, a temperature detecting device, and a humidity detecting device are integrated at low cost, when each sensing element is arranged on a substrate on which a drive circuit is mounted, it can be manufactured at low cost. , Technical issues come out. When the drive circuit and the intake air temperature / intake air humidity sensing element are formed on the same substrate, the drive circuit needs to be protected by the casing, and the sensing element needs to be exposed to the intake air. . The sensing element and the drive circuit need to be electrically connected by conductor wiring. In the manufacturing process, a probe pad for measurement is required for characteristic adjustment and quality confirmation of the sensing element.

  Normally, rubber parts are often used in the engine room of automobiles, and corrosive gas may be generated from the rubber parts. In addition, the air is suspended in the air by the air filter element provided in the air cleaner box. However, there is no gas trap effect and it is sucked into the engine. The engine oil exposed to high temperature may be vaporized and flow backward to the air cleaner box after the engine is stopped from other than air. Therefore, it exists in or passes through the intake air pipe downstream of the air cleaner box. The air you do is not always clean.

  Since it is placed in such an environment, it is necessary to improve the corrosion resistance. Further, as described above, since the density is increased, it is necessary to improve the mounting efficiency.

  Various hybrid IC substrates are known in which components such as a semiconductor integrated circuit, a capacitor, and a diode are mounted on a ceramic substrate. Among them, hybrid IC boards that use silver, silver alloy, copper, and copper alloys for conductor wiring, especially for hybrid IC boards that are used in in-vehicle sensors, are concerned about corrosion of conductor wiring due to corrosive gas, and are resistant to corrosion. A structure such as printing solder on the through-hole is considered as a measure to improve performance, but when a sensing element that is exposed to the intake air is mounted on a hybrid IC board, the inside and outside of the housing are electrically connected by conductor wiring. It is necessary to connect, and a part of the wiring conductor is also arranged outside the casing. It is also necessary to improve mounting efficiency by mounting the sensing element on the hybrid IC substrate. Japanese Patent Application Laid-Open No. 2006-258877 discloses the application of solder to the through-hole portion to mount an electronic component and the improvement of the corrosion resistance by wiring the gold conductor on the through-hole via and protecting it with glass. It is shown.

JP 2006-258777 A

  However, although Patent Document 1 considers the countermeasure against corrosion of the through-hole portion, it does not consider the countermeasure against corrosion of the conductor wiring. For this reason, there has been a problem that the conductor wiring is corroded by damaging the glass or the resin coat protecting the conductor wiring. In particular, when placing the drive circuit and each sensing element that measures intake air temperature and intake air humidity on the same board, place the case on the conductor wiring that connects the drive circuit inside the case and each sensing element exposed to intake air. There is a possibility that the coat may be damaged when the adhesive is fixed, and the conductor wiring is corroded. Further, when the driving circuit and each sensing element for measuring the intake air temperature and the intake air humidity are arranged on the same substrate, there arises a problem of improving the substrate mounting efficiency.

  Therefore, in view of the above problems, an object of the present invention is to provide an air flow rate measuring device with improved substrate mounting efficiency and improved corrosion resistance.

To achieve the above object, the physical quantity measuring device of the present invention, the sensing elements are provided for measuring the physical quantity of the air on the circuit board that an electronic circuit is formed, placing the electronic circuitry in the housing, In the physical quantity measuring device having a structure in which the sensing element is exposed to intake air, at least one insulating layer is provided between the circuit board and the glass or resin coating layer, and the connection between the sensing element and the electronic driving circuit is provided. Conductor wiring is disposed under the insulating layer, and the circuit board is a conductor multilayer printing by thick film printing, and a probe pad for adjusting characteristics or confirming characteristics of the sensing element is adhered on the circuit board. It is characterized in that it is arranged under the casing and covered with an adhesive .

  ADVANTAGE OF THE INVENTION According to this invention, the board | substrate mounting efficiency can be improved and the air flow measuring device which improved corrosion resistance can be provided.

The sensor structure which shows one Example of this invention. AA sectional drawing of Fig.1 (a). The elements on larger scale of FIG.1 (b). The system block diagram of an internal combustion engine. An example of the environment where the sensor is located. The structure diagram of a hybrid IC substrate. The structure diagram of a hybrid IC substrate. The structure diagram of a hybrid IC substrate. FIG.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1A and FIG. 1B are views showing a sensor structure and an AA cross section showing an embodiment of the present invention. FIG. 2 is a partially enlarged view of a sensor structure showing an embodiment of the present invention, FIG. 3 is a system configuration diagram of an internal combustion engine, and FIG. 4 is a diagram showing an embodiment of an environment where the sensor is placed.

  As shown in FIGS. 1A and 1B, the air flow rate measuring device 23 includes a base 2, a case 3, a cover 5, and a sub-passage constituting member 24. The base 2 is made of metal or resin, and the hybrid IC substrate 10 is fixed to the base 2 by adhesion or the like. Further, the base 2 constitutes a part of the sub-passage, and the sub-passage 25 is formed by fixing the base 2 and the sub-passage constituent member 24 by bonding or the like. Similarly, the case 3 and the base 2 are fixed by adhesion or the like. The electronic driving circuit 1 is covered by fixing the case 3 and the cover 5 by adhesion or the like.

  The hybrid IC substrate 10 is formed by printing and baking the conductor wiring 8 serving as a conductor of the electronic drive circuit 1 or the electronic control circuit, the resistance, etc. on the surface of the ceramic substrate 7 formed of an inorganic material such as ceramic. Yes. Most of the conductor wiring 8 is protected by glass or resin coating, except for the component mounting portion, probe pads such as potential and output. Furthermore, a capacitor, diode, semiconductor integrated circuit and a sensing element 9 for measuring physical quantities such as temperature and humidity are mounted on the surface.

  The case 3 is insert-molded with a terminal 12 made of a conductive member that controls transmission of an electrical signal inside the resin. The air flow rate measuring device 23 includes an intake air temperature detecting element 29 for measuring the intake air temperature in the outside or the sub passage 25, a heating resistor 11 for measuring a physical quantity such as an intake air flow rate, and a temperature sensitive resistance for temperature compensation. In this structure, the body 13 is installed. The intake air temperature detecting element 29, the heating resistor 11, and the temperature sensitive resistor 13 are respectively bonded to lead wires, and the lead wires are electrically and mechanically joined to the terminals. Then, it is electrically connected to the electronic drive circuit 1 through the terminal 12 by an aluminum wire bonding 26 or the like.

  Note that the air flow measuring device 23 using the heating resistor 11 and the temperature sensitive resistor 13 has a constant temperature difference between the heating resistor 11 and the temperature sensitive resistor 13 for measuring the air temperature by the circuit shown in FIG. The constant temperature is controlled by a constant temperature control circuit so as to be kept at a constant temperature.

  Next, as shown in FIG. 1A, the sensing element 9 for measuring physical quantities such as temperature and humidity mounted on the hybrid IC substrate 10 is connected to the electronic drive circuit 1 through the conductor wiring 8. ing. The drive circuit disposed on the hybrid IC board 10 is covered with the base 2, the case 3, and the cover 5, but the sensing element 9 for measuring physical quantities such as temperature and humidity is disposed so as to be exposed to the intake air. . Since the electronic drive circuit 1 is disposed in the case 3, it has a structure in which an adhesive is applied on the hybrid IC substrate 10 and the case 3 is bonded and fixed.

  As shown in FIG. 3, the heating resistor 11 and the temperature sensitive resistor 13 are arranged in an air cleaner 27 for flowing air sucked into the engine or in a rubber duct 21 provided downstream of the air cleaner 27, and In addition, an electrical signal is transmitted through a connector terminal embedded in the case 3.

  Here, as shown in FIG. 4, the interior of the engine room of the vehicle in which the air flow rate measuring device 23 is mounted has combustion gas blown back from the engine and unburned gas returned, and the atmosphere 19 where the hydrocarbon stays is present. Be exposed. Further, the interior of the engine room is a collection of products such as rubber ducts containing sulfur and (hose) 21 that are often arranged in engine components.

  Since the temperature of the electronic equipment inside the engine reaches a state exceeding 100 ° C., the sulfur simple substance gas or the sulfur compound gas 20 springs out from the product group vulcanized with sulfur such as the rubber duct 28 and the hose 21. In addition, these sulfur gases are transformed into the environment, and in some cases, the combustion gas is blown back, the return gas of the unburned gas is mixed with the hydrocarbon, and a mixed gas state is present. , It may not be a reliable product. The conductor wiring 8 formed on the hybrid IC substrate 10 in the air flow measuring device 23 is formed of silver or a silver alloy, and corrosive gas, particularly sulfur gas or sulfur compound gas 20 has entered the case 3. In this case, the silver or silver alloy wiring portion that becomes the conductor wiring 8 is subject to sulfidation corrosion, and the electronic drive circuit 1 may not operate normally.

  Further, since the sensing element 9 is disposed in a state exposed to the intake air, a part of the conductor wiring 8 that connects the sensing element 9 and the electronic drive circuit 1 or the electronic control circuit is disposed outside the case 3. By disposing the conductor wiring 8 outside the case, if the conductor wiring 8 is exposed, there is a possibility that corrosion breakage may occur. Since the sulfide corrosion of the conductor wiring 8 occurs from the exposed portion of the conductor wiring 8, it is necessary to improve the corrosion resistance by preventing the exposure.

  The bonding portion of the case 3 is an upper portion of the conductor wiring 8 that connects the sensing element 9 for measuring physical quantities such as temperature and humidity and the electronic driving circuit 1. When the case 3 is mounted on the hybrid IC substrate 10, There is a possibility that the glass or resin coat protecting the conductor wiring 8 of the IC substrate 10 may be damaged. When the coat is damaged, corrosive gas enters from there and corrodes the conductor wiring.

  From this, as shown in FIG. 2, in order to prevent the situation where the conductor wiring leads to corrosion disconnection, the upper surface of the conductor wiring 15 connecting the sensing element 9 for measuring physical quantities such as temperature and humidity and the electronic drive circuit. In addition to the protective glass 14 or the resin coat, one or more insulating layers 16 were disposed. Thereby, corrosion resistance can be improved.

  Further, in the manufacturing process, it is necessary to check the characteristics of the sensing element 9 for measuring physical quantities such as temperature and humidity, or to check the characteristics such as operation, and the probe pad 17 for measurement is provided. In one embodiment of the present invention, the adhesive 18 is applied on the probe pad 17 for this measurement, and the hybrid IC substrate 10 and the sandwich structure are formed in the case 3. By adopting such a structure, the hybrid IC substrate mounting efficiency can be improved and the corrosion resistance can be improved.

  5 to 7 are diagrams showing the configuration of the hybrid IC substrate 10.

  When the adhesive 18 is applied on the hybrid IC substrate 10 and the case 3 is bonded, management of the application position of the adhesive becomes important. Therefore, in this embodiment, in the hybrid IC substrate by thick film printing, the mark 22 for reducing the positional deviation at the time of printing is attached. By using this mark as a mark for the adhesive application position, it is possible to easily confirm the adhesive application position by an automatic machine or by visual observation.

  In addition, the mark of the adhesive application position is arranged with a conductor that does not form a drive circuit. Thereby, it is possible to facilitate confirmation of the adhesive application position with an automatic machine or visual inspection.

  Furthermore, by arranging with a conductor, the conductor used as a mark corrodes first, and corrosive gas intrusion to the probe pad portion can be suppressed.

DESCRIPTION OF SYMBOLS 1 Electronic drive circuit 2 Base 3 Case 4 Bonding sealing part 5 of base and case Cover 6 Bonding sealing part of case and cover 7 Ceramic substrate 8 Conductor wiring 9 Sensing element 10 Hybrid IC substrate 11 Heating resistor 12 Terminal 13 Temperature sensing Resistor 14 Protective glass 15 Conductor wiring 16 for connecting the sensing element and the drive circuit Insulating layer 17 Probe pad 18 Adhesive 19 Hydrocarbon atmosphere 20 Sulfur compound gas 21 Rubber duct 22 Misalignment prevention mark 23 Air flow measuring device 24 Sub-passage component 25 Sub-passage 26 Aluminum wire bonding 27 Air cleaner 28 Rubber duct

Claims (3)

Sensing elements are provided for measuring the physical quantity of the air on a circuit board electronic circuit is formed, the electronic circuit is arranged in the housing, in the physical quantity measuring device having a structure exposing the sensing element to the intake air,
Providing at least one insulating layer between the circuit board and the glass or resin coat layer, and arranging a conductor wiring for connecting the sensing element and the electronic drive circuit under the insulating layer,
The circuit board is a conductor multilayer printing by thick film printing,
A physical quantity measuring apparatus characterized in that a probe pad for adjusting characteristics or confirming characteristics of the sensing element is arranged under a casing to be bonded to a circuit board and covered with an adhesive . A misregistration prevention mark for preventing misregistration of the thick film printing is provided on the circuit board, and the misregistration prevention mark is used as an application position target of an adhesive applied on the circuit board. The physical quantity measuring device according to claim 1 . The physical quantity measuring apparatus according to claim 1, wherein the application position target of the adhesive applied on the circuit board is formed of a conductor that does not form a circuit.

Images