Packaging structure of intelligent gas sensor control box and packaging method thereof

Abstract

The invention relates to the technical field of sensors, in particular to a packaging structure of an intelligent gas sensor control box and a packaging method of the packaging structure. Pins and wires are arranged in the control shell, the Pins and the wires are connected in a one-to-one correspondence mode, the portion, located on the outer side of the control shell, of each wire is connected with a wire harness fixing mechanism connected to the outer side of the control shell, the PCBA board is arranged in the control shell and connected with the Pins, and the control shell is connected with the lower cover plate. According to the packaging structure of the intelligent gas sensor control box, by adding the wire harness fixing block structure, the problem of dull semi-finished products caused by multiple wire length specifications in the manufacturing process can be solved, the production efficiency is improved, a waterproof plug structure is further adopted for wire harness fixing, and pressing sealing is achieved; compared with a clamping connection mode, an electric resistance welding mode or an argon arc welding mode, the manufacturability and the efficiency of laser welding of the copper Pin and the nickel-based wire are higher; and the air holes are added, so that the influence of the heating value of a large component on internal air pressure is reduced.

Description

Technical Field

[0001] The invention relates to a packaging structure, and in particular to a packaging structure of an intelligent gas sensor control box and a packaging method thereof. Background Art

[0002] Smart gas sensors are commonly used in the automotive and industrial fields to detect gas temperature, gas composition (H2O, O2, NOx, CO2, etc.) concentration and other information, and feed back to the integrated control system for control logic judgment. Smart gas sensors are usually composed of a sensing probe capable of detecting the physical quantity of the gas and a control unit for signal processing, control and transmission. In actual application, the sensor line length specifications vary, and the requirements for flexible production are getting higher and higher. It is necessary to solve the problems of too many stagnant semi-finished products, low production efficiency and long production cycle. In actual application, the sensor line length specifications vary, and the requirements for flexible production are getting higher and higher; in addition, compared with the wiring harness connection methods of clamping, resistance welding or argon arc welding, the manufacturability and efficiency are lower; at the same time, it is necessary to solve the problems of too many stagnant semi-finished products and long production cycle. Summary of the invention

[0003] The present invention aims to solve the above-mentioned defects and provides a packaging structure and a packaging method of an intelligent gas sensor control box.

[0004] In order to overcome the defects existing in the background technology, the technical solution adopted by the present invention to solve the technical problem is: the packaging structure of the intelligent gas sensor control box includes a control shell, a PCBA board, a lower cover and a wiring harness fixing mechanism, at least one wiring harness is arranged in the control shell, each wiring harness includes a wire 1 and a wire 2 which are positive and negative wires, and a wiring harness fixing mechanism fixing one end of the wire 1 and the wire 2, the control shell includes a plastic shell and a pin needle group fixed in the plastic shell with the same number as the wiring harness, each pin needle group includes a pin needle 1 and a pin needle 2, the pin needle 1 is connected to the other end of the wire 1 by laser melting and coating, the pin needle 2 is connected to the other end of the wire 2 by laser melting and coating, the wiring harness fixing mechanism is located on the outside of the control shell, the PCBA board is placed in the control shell and connected to each pin of the pin needle group, and the control shell is connected to the lower cover.

[0005] According to another embodiment of the present invention, the wiring harness fixing mechanism is further included as a split assembly type, including wiring harness claw one and wiring harness claw two, wiring harness claw one and wiring harness claw two are provided with a connecting plane section and a receiving cavity for accommodating one end of wire one and wire two, wiring harness claw one and wiring harness claw two are welded together at the connecting plane section by friction welding or ultrasonic welding, and a waterproof plug is provided on wire one and wire two located on the outer part of the control shell.

[0006] According to another embodiment of the present invention, the Pin pins of the Pin pin group are further C-shaped, one end of which is provided with a through hole for connecting a wire, and the other end is provided with a pointed head connected to a PCBA board, and the PCBA board is provided with holes for connecting the Pin pins, and the holes are arranged in a straight line.

[0007] According to another embodiment of the present invention, the pins of the pin pin group are further fixed to the plastic shell of the control shell by integral injection molding.

[0008] According to another embodiment of the present invention, the material of the wire 1 and the wire 2 on each group of wiring harness is a nickel-based alloy, the material of the Pin 1 and the Pin 2 of each group of Pin needle groups is pure copper or copper alloy, and the Pin 1 and the Pin 2 of each group of Pin needle groups are provided with a single-layer or multi-layer combined plating of Ni, Sn or Zn.

[0009] According to another embodiment of the present invention, the control shell is further provided with a ventilation hole 1 which is connected with the plug interface outside the control shell, and a ventilation membrane 1 is provided on the ventilation hole 1.

[0010] According to another embodiment of the present invention, the control housing further comprises a second air vent hole connected to the outside provided on the side wall thereof, and a second air permeable membrane provided on the second air vent hole.

[0011] A packaging method for an intelligent gas sensor control box, the packaging method comprising: The first step is to prepare a number of pin groups corresponding to the wiring harness, place the pin group consisting of pin one and pin two on the mold for positioning, and form a control shell by integral injection molding with the plastic shell; The second step is to assemble the wiring harness. First, cut the wires of the corresponding wire length specifications on all the wiring harnesses, peel the connection ends of the corresponding pins of the wires 1 and 2 on each set of wiring harnesses. The wires 1 and 2 of each set of wiring harnesses are positive and negative wires. After fixing the wires along the preset wire fixing grooves, one end of the wires 1 and 2 of each set of wiring harnesses is fastened to a wiring harness fixing mechanism, and then welded together by friction welding / ultrasonic welding, etc. After each wire is inserted into the waterproof plug, it is inserted into the corresponding sealing hole of the control shell, and the wiring harness fixing mechanism is clamped; The third step is to connect the wires of each set of wiring harnesses to the pins. After the exposed metal part of the wire peeled in the second step is inserted into the through hole on the pin, the inert protective gas is purged, and the laser melts the metal on the upper part of the pin through hole into droplets and covers the surface of the wire. After cooling, the covering connection is achieved, and the connection and fixation between each wire and the pin are completed in sequence; Step 4: Install the PCBA board and connect the tip of each pin of the pin needle group to the hole set on the PCBA board by soldering.

[0012] Step 5. Finally, install the lower cover plate. Friction welding, ultrasonic welding, laser welding, etc. are used to seal and fix the lower cover plate and the control shell.

[0013] According to another embodiment of the present invention, the inert protective gas purged in the third step is nitrogen or argon, and when a gas pipeline with an inner diameter of 4 mm is used for purging, the purging pressure is 0.1-1 MPa.

[0014] According to another embodiment of the present invention, further including in the third step when the laser melts the upper metal of the Pin needle through hole, the laser needs to adopt line scanning continuous light emission and negative focus mode. During line scanning, the laser spot acts on the central part of the molten end face of the copper Pin needle and covers a certain area, specifically, it should occupy 50%-90% in the length direction and 50-80% in the width direction.

[0015] The beneficial effects of the present invention are as follows: the packaging structure of the intelligent gas sensor control box can solve the problem of sluggish semi-finished products caused by multiple wire length specifications during the manufacturing process by adding a wire harness fixing block structure, thereby improving production efficiency; the wire harness fixing also adopts a waterproof plugging structure to achieve compression sealing; the Pin needle and the wire are connected by laser melting and coating to improve reliability and production efficiency; and air holes are added to reduce the influence of the heat generated by larger components on the internal air pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0017] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a partial structural schematic diagram of the present invention; Among them: 1. Lower cover, 2. PCBA board, 3. Control shell, 4. Wire one, 5. Wire harness claw one, 6. Wire two, 7. Pin two, 8. Wire harness claw two, 9. Waterproof plug, 10. Hole, 11. Pin one, 12. Pointed head, 13. Through hole, 14. Plug interface, 15. Air hole one, 16. Air membrane one, 17. Air hole two, 18. Air membrane two, 19. Wire harness fixing mechanism. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] This intelligent gas sensor control box packaging structure is suitable for automotive and industrial applications. The intelligent gas sensor adopts a modular packaging process to meet flexible production needs and improve product packaging efficiency and reliability. Figure 1 As shown, it includes a control shell 3, a PCBA board 2, a lower cover 1 and a harness fixing mechanism 19. At least one harness is arranged in the control shell 3. Each harness includes a positive and negative wire 14 and a wire 2 6, and a harness fixing mechanism 19 fixing one end of the wire 1 4 and the wire 2 6. The control shell 3 includes a plastic shell and a pin group fixed in the plastic shell with the same number of harnesses. Each pin group includes a pin 11 and a pin 2 7. The pin 11 is connected to the other end of the wire 1 4 by laser melting and coating, and the pin 2 7 is connected to the other end of the wire 2 6 by laser melting and coating. The harness fixing mechanism 19 is located outside the control shell 3. The PCBA board 2 is placed in the control shell 3 and connected to each pin of the pin group. The control shell 3 is connected to the lower cover 1. The connection between the pin and the PCBA board is soldered, and the lower cover 1 and the control shell 3 are sealed and fixed by friction welding, ultrasonic welding, laser welding or sealant.

[0020] The wiring harness fixing mechanism 19 is a split assembly type, including a wiring harness claw 1 5 and a wiring harness claw 2 8. The wiring harness claw 1 5 and the wiring harness claw 2 8 are provided with a connecting plane section and a receiving cavity for accommodating the wire 1 4 and the wire 2 6. The wiring harness claw 1 5 and the wiring harness claw 2 8 are welded together at the connecting plane section by friction welding or ultrasonic welding. The waterproof plug 9 is sleeved on the wire 1 4 and the wire 2 6 located on the outer part of the control shell 3, and a waterproof plug is used between the wire and the control shell to achieve compression sealing.

[0021] The pin of the pin group is C-shaped, with a through hole for connecting the wire at one end and a pointed tip for connecting to the PCBA board at the other end. The PCBA board 2 is provided with holes 10 for connecting the pins, and the holes 10 are arranged in a straight line. The connection method between the pin of the pin group and the wire is laser melting and cladding connection, such as Figure 1 As shown, for laser welding, after the wire is inserted into the pin hole, the laser is used to melt the metal on the upper part of the pin hole to form droplets to fill the gap in the hole, and then the droplets are welded together with the wire after cooling. When the pin and the wire are made of pure copper or copper alloy or nickel-based alloy, the nickel-based wire is peeled and the exposed metal part is inserted into the copper pin hole, and then an inert protective gas such as nitrogen or argon is purged. The laser melts the metal on the upper part of the pin hole into droplets and covers the surface of the nickel-based wire, and then the wire is welded and fixed after cooling.

[0022] The pins of the pin group are fixed by integral injection molding with the plastic shell of the control shell 3. First, all the pins are placed on the mold and positioned, and are integrally injection molded with the plastic shell. After the injection molding is completed, the pins and the plastic shell become one body to form the control shell 3, and the wires of the wiring harness are inserted into the inside through the holes on the control shell 3, and the insertion ends of the wires are inserted into the through holes on the pins for connecting the wires.

[0023] In order to reduce the influence of the heat generated by the larger components on the internal air pressure, the control shell 3 is provided with a vent hole 15 connected to the plug interface 14 outside the control shell 3, and a vent film 16 is provided on the vent hole 15; or a vent hole 2 17 connected to the outside is provided on the side wall of the control shell 3, and a vent film 2 18 is provided on the vent hole 17. Figure 2 shown.

[0024] The number of Pin 11 and Pin 2 7 is equal and arranged in parallel. The connection point of the wire and the Pin is arranged in the same side space of the PCBA, so that the temperature of the connection point is kept as close as possible to the temperature of the PCBA, solving the accuracy deviation caused by the large deviation between the cold end compensation point of the thermocouple temperature sensor and the actual cold end point temperature.

[0025] Packaging method of intelligent gas sensor control box: The first step is to prepare a number of pin groups corresponding to the wiring harness, place the pin group consisting of pin one 11 and pin two 7 on the mold for positioning, and form a control shell 3 by integral injection molding with the plastic shell; The second step is to assemble the wiring harness. First, cut the wires of the corresponding wire length specifications on all the wiring harnesses, peel the connection ends of the wires 1 4 and 2 6 on each group of wiring harnesses corresponding to the corresponding pins, and the wires 1 4 and 2 6 of each group of wiring harnesses are positive and negative wires. After fixing the wires along the preset wire fixing grooves, one end of the wires 1 4 and 2 6 of each group of wiring harnesses is fastened to a wire harness fixing mechanism 19, and then welded together by friction welding / ultrasonic welding, etc. After each wire is inserted into the waterproof plug, it is inserted into the corresponding sealing hole of the control shell, and the wire harness fixing mechanism 19 is clamped. All wiring harnesses are assembled according to this step; The third step is to connect the wires of each group of wire harnesses to the pin needles. After the exposed metal part of the wire peeled in the second step is inserted into the through hole on the pin needle, the inert protective gas is purged, and the laser melts the metal on the upper part of the pin needle through hole into droplets and covers the surface of the wire. After cooling, the covering connection is realized, and the connection and fixation between each wire and the pin needle are completed in sequence, that is, the pin needle 11 is connected to the other end of the wire 14 by laser melting and covering, and the pin needle 27 is connected to the other end of the wire 26 by laser melting and covering; Step 4: Install the PCBA board 2, and connect the tip 12 on each pin of the pin needle group to the hole set on the PCBA board 2 by soldering.

[0026] Step 5: Finally, install the lower cover plate 1. Friction welding, ultrasonic welding, laser welding, etc. are used to seal and fix the lower cover plate 1 and the control shell 3.

[0027] Since copper and copper alloys have high thermal conductivity, local heat is easily lost by conduction, and molten droplets splash, etc., it is difficult to use laser technology to achieve stable and reliable connection between dissimilar metals. The packaging method of the intelligent gas sensor control box of the present invention uses laser melting and cladding connection to connect Pin 11, Pin 2 7 and the wire.

[0028] After the nickel-based wire is peeled and the exposed metal part is inserted into the copper pin hole, the inert protective gas, such as nitrogen, argon, etc., is purged, and the laser melts the metal on the upper part of the pin hole into droplets and coats the surface of the nickel-based wire. After cooling, the connection is fixed. After the melt coating, the average tension between the copper pins of the wire should be ≥165N / root, the coating appearance should be round and smooth, the coating cross-section should be ≥1 / 2 of the wire cross-section, and there should be basically no splashing droplets.

[0029] The material of the pin is pure copper or copper alloy; the material of the wire is nickel-based alloy. For the N-type thermocouple, the positive and negative compensation wires are made of NiCrSi and NiSiMg respectively, and the thermal conductivity at 100°C is 0.0358 and 0.0664 cal.cm / s.cm respectively. 2 ℃.

[0030] When laser melting the upper metal of the copper pin through-hole, it is necessary to purge inert gas. When the purge gas flow rate and velocity are low, the molten coating state will be not round and smooth, and copper metal oxidation will occur; when the purge gas flow rate and velocity are high, copper droplets will splash, which is difficult to clean and has the potential risk of short circuit. For a gas pipeline with an inner diameter of 4mm, the purge pressure is 0.1-1MPa, preferably 0.2-0.5MPa. The specific comparison of the inert gas purge pressure and the molten coating appearance and tensile force average is shown in the following table:

[0031] When laser melting the upper metal of the copper pin through-hole, the laser needs to use line scanning continuous light emission and negative focus. During line scanning, the laser spot acts on the center of the copper pin's molten end face and covers a certain area, specifically 50%-90% in the length direction and 50-80% in the width direction. The degree of centering and the area of ​​the laser acting on the end face will directly affect the amount of molten metal, the coating state and the average tensile force. That is, if the laser action area deviates too much from the center, the amount of molten metal will be reduced, and laser ablation will damage the control shell; if the laser action area is too small, the amount of molten metal will be reduced and the coating state will deteriorate. The comparison between the specific laser spot action end face area and the molten coating appearance and the average tensile force is shown in the following table:

[0032] At room temperature, only about 3%-5% of the incident laser is absorbed in the initial stage of the laser acting on the copper surface, and the rest is reflected. If the laser energy is greatly increased to compensate for the problem of low laser absorption rate, the absorption rate will easily increase after the copper melts into droplets, causing excessive local energy and splashing of droplets. In order to increase the absorption rate of the pin to the laser and reduce the splashing of droplets, the surface of the copper pin needle should be plated, and the preferred ones are single-layer or multi-layer combination coatings such as Ni, Sn, and Zn.

[0033] In order to improve the consistency and yield of the melt-coated connection, it is necessary to use a tool to press the exposed metal part of the wire against the lower semicircular area at the bottom of the copper pin needle through-hole. When the laser melts the metal on the upper part of the copper pin needle through-hole to form a droplet that moves downward under the influence of gravity and contacts the wire, the heat of the droplet is quickly dissipated through the metal part of the wire and cools and solidifies. If there is still a large gap at the bottom of the copper pin needle through-hole, the droplet will not have time to fill the entire gap, resulting in a reduction in the coated wire area and a decrease in the average tension, affecting the connection reliability. The effect of the gap between the wire and the bottom of the copper pin needle through-hole on the appearance of the melt-coated and the average tension is shown in the following table:

[0034] The thermal conductivity of the wire will also affect the coating effect after melting. Taking the positive and negative electrodes of the N-type thermocouple compensation wire as an example, the thermal conductivity of the positive electrode is about half of that of the negative electrode, and the corresponding positive electrode wire laser light energy should be lower than the negative electrode laser light energy.

[0035] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A packaging structure of an intelligent gas sensor control box, comprising a control housing (3), a PCBA board (2), a lower cover (1) and a wiring harness fixing mechanism (19), characterized in that: The control shell (3) is provided with at least one wire harness, each wire harness comprises a positive wire (4) and a negative wire (6), and a wire harness fixing mechanism (19) fixing one end of the wire (4) and the wire (6). The control shell (3) comprises a plastic shell and a pin group fixed in the plastic shell and having the same number as the wire harness. Each pin group comprises a pin one (11) and a pin two (7). The pin one (11) is connected to the other end of the wire one (4) by laser melting and cladding, and the pin two (7) is connected to the other end of the wire two (6) by laser melting and cladding. The wire harness fixing mechanism (19) is located outside the control shell (3). The PCBA board (2) is placed in the control shell (3) and connected to each pin of the pin group. The control shell (3) is connected to the lower cover plate (1).

2. The packaging structure of an intelligent gas sensor control box according to claim 1, characterized in that: The harness fixing mechanism (19) is of a split assembly type, comprising a harness clamping claw 1 (5) and a harness clamping claw 2 (8), wherein the harness clamping claw 1 (5) and the harness clamping claw 2 (8) are provided with a connecting plane section and a receiving cavity for receiving and placing one end of the wire 1 (4) and the wire 2 (6), wherein the harness clamping claw 1 (5) and the harness clamping claw 2 (8) are welded together at the connecting plane section by friction welding or ultrasonic welding, and a waterproof plug (9) is sleeved on the wire 1 (4) and the wire 2 (6) located on the outer part of the control housing (3).

3. The packaging structure of an intelligent gas sensor control box according to claim 1, characterized in that: The pins of the pin pin group are C-shaped, one end of which is provided with a through hole for connecting a wire, and the other end of which is provided with a pointed end for connecting to the PCBA board. The PCBA board (2) is provided with holes (10) for connecting the pins, and the holes (10) are arranged in a straight line.

4. The packaging structure of an intelligent gas sensor control box according to claim 1, characterized in that: The pins of the pin pin group are integrally fixed to the plastic shell of the control shell (3) by injection molding.

5. The packaging structure of an intelligent gas sensor control box according to claim 1, characterized in that: The material of the wire 1 (4) and the wire 2 (6) on each group of wiring harnesses is a nickel-based alloy, the material of the pin 1 (11) and the pin 2 (7) of each group of pin needle groups is pure copper or a copper alloy, and the pin 1 (11) and the pin 2 (7) of each group of pin needle groups are provided with a single layer or a multi-layer combined coating of Ni, Sn or Zn.

6. The packaging structure of an intelligent gas sensor control box according to claim 1, characterized in that: The control shell (3) is provided with a ventilation hole (15) in communication with an insertion interface (14) outside the control shell (3), and a ventilation membrane (16) is provided on the ventilation hole (15).

7. The packaging structure of an intelligent gas sensor control box according to claim 1, characterized in that: A second vent hole (17) communicating with the outside is provided on the side wall of the control housing (3), and a second vent membrane (18) is provided on the second vent hole (17).

8. The packaging method of the intelligent gas sensor control box according to claim 1, characterized in that: The packaging method includes: The first step is to prepare a number of pin groups corresponding to the number of wiring harnesses, place the pin group consisting of pin one (11) and pin two (7) on the mold for positioning, and form a control shell (3) by integral injection molding with the plastic shell; Step 2: assemble the wiring harness. First, cut the wires of corresponding length specifications on all the wiring harnesses, peel the connection ends of wire 1 (4) and wire 2 (6) on each set of wiring harnesses corresponding to the corresponding pins, respectively. Wire 1 (4) and wire 2 (6) of each set of wiring harnesses are positive and negative wires. After fixing the wires along the preset wire fixing grooves, one end of wire 1 (4) and wire 2 (6) of each set of wiring harnesses is fastened to a wiring harness fixing mechanism (19), and then welded together by friction welding / ultrasonic welding, etc. After each wire is inserted into the waterproof plug, it is inserted into the corresponding sealing hole of the control shell, and the wiring harness fixing mechanism (19) is clamped. All wiring harnesses are assembled according to this step; The third step is to connect the wires of each set of wiring harnesses to the pins. After the exposed metal part of the wire peeled in the second step is inserted into the through hole on the pin, the inert protective gas is purged, and the laser melts the metal on the upper part of the pin through hole into droplets and covers the surface of the wire. After cooling, the covering connection is achieved, and the connection and fixation between each wire and the pin are completed in sequence; Step 4: insert the PCBA board (2), and connect the pointed end (12) on each pin of the pin group to the hole set on the PCBA board (2) by soldering; Step 5: Finally, the lower cover plate (1) is installed. The lower cover plate (1) and the control housing (3) are sealed and fixed by friction welding, ultrasonic welding, laser welding, etc.

9. The packaging method of the intelligent gas sensor control box according to claim 1, characterized in that: The inert protective gas used for purging in the third step is nitrogen or argon. When a gas pipeline with an inner diameter of 4 mm is used for purging, the purging pressure is 0.1-1 MPa.

10. The packaging method of the intelligent gas sensor control box according to claim 1, characterized in that: When the laser melts the metal on the upper part of the Pin needle through hole in the third step, the laser needs to adopt line scanning continuous light emission and negative focus mode. During line scanning, the laser spot acts on the central part of the molten end face of the copper Pin needle and covers a certain area, specifically 50%-90% in the length direction and 50-80% in the width direction.

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