CN107333384B - Circuit board assembly of liquid level detection device and installation method thereof - Google Patents
Circuit board assembly of liquid level detection device and installation method thereof Download PDFInfo
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- CN107333384B CN107333384B CN201710493822.1A CN201710493822A CN107333384B CN 107333384 B CN107333384 B CN 107333384B CN 201710493822 A CN201710493822 A CN 201710493822A CN 107333384 B CN107333384 B CN 107333384B
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- substrate
- circuit board
- board assembly
- sealing sleeve
- magnetic induction
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0277—Bendability or stretchability details
- H05K1/028—Bending or folding regions of flexible printed circuits
- H05K1/0281—Reinforcement details thereof
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/30—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by floats
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/18—Printed circuits structurally associated with non-printed electric components
- H05K1/189—Printed circuits structurally associated with non-printed electric components characterised by the use of a flexible or folded printed circuit
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/0058—Laminating printed circuit boards onto other substrates, e.g. metallic substrates
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K5/00—Casings, cabinets or drawers for electric apparatus
- H05K5/06—Hermetically-sealed casings
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10007—Types of components
- H05K2201/10151—Sensor
Abstract
The invention discloses a circuit board assembly of a liquid level detection device, which comprises a magnetic induction element, a first substrate and a second substrate, wherein the first substrate is a flexible substrate, and the magnetic induction element is arranged on the first substrate; the second substrate is a nonmagnetic substrate, the hardness of the second substrate is greater than that of the first substrate, and the first substrate is fixed on the second substrate. According to the invention, the magnetic induction element is arranged on the flexible substrate, so that the winding storage is facilitated, and the later-stage assembly is facilitated; the invention also discloses a method for mounting the circuit board assembly, wherein the first substrate and the second substrate are fixedly connected through the third substrate with a buffering effect, so that the first substrate is prevented from being damaged by stress, the method is simple and practical, and the mounting efficiency and the mounting quality of the circuit board assembly are improved.
Description
Technical Field
The invention relates to the technical field of liquid level sensors, in particular to a circuit board assembly of a liquid level detection device and an installation method thereof.
Background
At present, current floater level sensor is mostly tongue tube float sensor, and the test tube centre dress of this sensor is equipped with a plurality of tongue tubes, when the floater floated along the test tube along the liquid level from top to bottom for the tongue tube action of different positions, thereby makes the resistance of sensor output change, then converts the resistance that changes into other signal display for the user on the controller.
The utility model discloses a utility model application number is 91216416.6's utility model discloses a reed switch formula floater level sensor, by the flotation pontoon, the floater, permanent magnet steel and N group reed switch are constituteed, each group reed switch is placed according to the horizontal direction and is welded on the flush mounting plate, the flush mounting plate is fixed in the sealed cubical switchboard, wherein each group reed switch's one end is altogether (0 volt), the other end directly connects to on the input of instrument, connect to the power (+5 volts) through a resistance respectively at each input of instrument side simultaneously, every group reed switch position corresponds height value of liquid level. The reed pipe is arranged in the patent as a magnetic induction element, the operating principle of the reed pipe is that two magnetizable reeds overlapped at end points are arranged and sealed in a glass pipe, the distance separating the two reeds is only about a few micrometers, high-purity inert gas is filled in the glass pipe, when the reed pipe is not operated, the two reeds are not contacted, an external magnetic field enables the positions near the end points of the two reeds to generate different polarities, and as a result, the two reeds with different polarities attract each other and are closed, however, the reeds in the reed pipe are in the state that the content of the magnetic field is easily magnetized for a long time, so that the detection accuracy and the service life of the liquid level detection device are influenced, on the other hand, the reed pipe is fragile including the glass pipe and is easily damaged.
The utility model discloses an application number is 201620554866.1's utility model patent type discloses a linear hall floater level sensor, including the measuring pole, fixed setting in this measuring pole linear hall element, along with the fluctuation of liquid level and float and drive and produce relative displacement's magnet with this linear hall element by this float, this linear hall element can realize linear voltage output along with the displacement of magnet. The sensor comprises a straight sliding type and a rotary type linear Hall floating ball liquid level sensor. The direct-sliding type linear Hall floating ball liquid level sensor is characterized in that a floater drives a magnet to slide up and down on a detection rod, the magnet and a linear Hall element generate relative displacement, liquid level monitoring is achieved, and continuous analog signals are output. The carrier used for connecting each linear Hall element is a PCB hard printed circuit board, each Hall element is vertically connected to the PCB hard printed circuit board, however, the hardness of the PCB is large, the shearing of the first substrate is not facilitated when the liquid level sensor is assembled, and the storage of the produced first substrate is also not facilitated. When the PCB is used as a substrate of the magnetic induction element, a plurality of PCB printed circuit boards need to be placed in parallel when being stored, the occupied space is large, and the PCB printed circuit boards are easy to rub and extrude, so that the magnetic induction element is damaged.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention provides a circuit board assembly of a liquid level detection device, which aims to overcome the defects of the prior art and is beneficial to winding storage and later assembly by arranging a magnetic induction element on a flexible substrate.
In order to solve the technical problems, the invention adopts the technical scheme that:
a circuit board assembly of a liquid level detection device comprises a magnetic induction element, a first substrate and a second substrate, wherein the first substrate is a flexible substrate, and the magnetic induction element is arranged on the first substrate; the second substrate is a nonmagnetic substrate, the hardness of the second substrate is greater than that of the first substrate, and the first substrate is fixed on the second substrate.
In the scheme, the magnetic induction element is arranged on the flexible substrate, so that winding storage is facilitated, and later-stage assembly is facilitated.
Preferably, the first substrate and the second substrate are both strip-shaped structures, one surface of the first substrate is fixed with the magnetic induction element, and the other surface of the first substrate is directly fixed on the second substrate or fixed on the second substrate through a connecting structure;
preferably, the length of the first substrate is smaller than that of the second substrate;
preferably, the width of the first substrate is not greater than the width of the second substrate;
in the above scheme, the width of the first substrate is not greater than the width of the second substrate, so that the first substrate can be fixed on the second substrate conveniently, and the second substrate can protect the first substrate conveniently.
Preferably, the second substrate has substantially the same coefficient of expansion and contraction as the first substrate.
In the above scheme, setting the expansion coefficient of the second substrate to be the same as that of the first substrate is beneficial to the second substrate to protect the first substrate, and shares the stress with the first substrate, for example: when the expansion coefficient of the second substrate is larger than that of the first substrate, the second substrate is seriously deformed by heating and the first substrate is less deformed in a hot environment application scene, but the first substrate is fixed on the second substrate, so that the first substrate can be easily damaged by tensile force in the deformation of the second substrate, the service life of the first substrate is shortened, and the application field of the circuit board assembly is limited. When the expansion coefficients of the second substrate and the first substrate are the same, the first substrate and the second substrate deform synchronously in the same environment, so that the first substrate is prevented from being damaged by stress. It should be noted that the coefficient of expansion and contraction referred to in the present invention means: the rate of change of the dimensions of the material in different environments. Wherein the external environment comprises an environmental temperature value and/or a stress condition of the material. Proportion, when this circuit board subassembly stretches, then because the elongation of second base plate equals first base plate to when this circuit board subassembly received the tensile force, first base plate and second base plate atress simultaneously warp in step, share the pulling force jointly, thereby prevented that first base plate atress alone is impaired.
Preferably, the circuit board assembly of the liquid level detection device further comprises a third substrate, the third substrate is made of an elastic material, and the first substrate is fixed on the second substrate through the third substrate;
preferably, the third substrate is a buffer substrate and is used for absorbing the deformation stress of the first substrate and/or the second substrate;
in the above scheme, because the third substrate is made of an elastic material, the third substrate has a buffering effect, when the first substrate and the second substrate are deformed by an external force, the third substrate can absorb the deformation stress of the first substrate and the second substrate, so that the coordination of the stress of the first substrate and the second substrate is facilitated, and the first substrate is prevented from being damaged by the external force alone.
Preferably, the thickness of the third substrate is greater than the first substrate and the second substrate, and more preferably, the ratio of the thicknesses of the first substrate, the second substrate and the third substrate is 1: (1-5): (1-15);
preferably, in the above solution, because the third substrate needs to provide a buffering force, and has a certain requirement on the thickness thereof, through a lot of experiments, the inventor finds that, in the process of assembling the circuit board assembly at ordinary times, when the thickness of the third substrate is within a certain range, a better buffering effect can be achieved, where the range is: the ratio of the thicknesses of the first substrate, the second substrate and the third substrate is 1: (1-5): (1-15).
Preferably, both surfaces of the third substrate are provided with a bondable structure, one surface is used for being bonded and fixed with the first substrate, and the other surface is used for being bonded and fixed with the second substrate;
in the scheme, the substrates are connected and fixed in an adhesion mode, and the method is simple, stable and low in cost.
Preferably, the heat-resistant temperature range of the third substrate is-40 to 200 °;
in the above solution, because the circuit board assembly is applied in a complex situation and different external environments, the circuit board assembly may be used in a high temperature environment or a low temperature environment, and therefore, the heat-resistant temperature of the third substrate needs to meet the above requirements to support the circuit board assembly to be applied in various fields.
Preferably, the third substrate is a double-sided adhesive tape;
preferably, the first substrate is a flexible circuit board, the second substrate is a non-magnetic metal substrate or a non-metal substrate, and the magnetic induction element is a tunnel magneto-resistance sensor or a hall element. In the invention, because the first substrate is a flexible substrate and the existing reed switch is easy to be damaged by stress, the Hall element or the tunnel magneto-resistance sensor is selected as the magnetic induction element, and the service life of the tunnel magneto-resistance sensor or the Hall element is forty thousand times of that of the reed switch. According to the invention, the magnetic induction element is a tunnel magneto-resistance sensor or a Hall element, and is more suitable for the flexible circuit board, because the glass tube of the reed pipe is fragile and is arranged on the flexible circuit board, the reed pipe is easy to shake and collide, and then the reed pipe can be wound into a disc-shaped structure when the flexible circuit board is stored, so that the space is saved, and the reed pipe is easy to break under the action of external force when the flexible circuit board is bent. When the Hall element is welded on the flexible circuit board, pins are not needed for welding to be formed, the Hall element is not broken, the welding is convenient, the Hall element can be produced in large scale in batch, the labor force is saved, the problem of breaking of the magnetic induction element cannot occur in the debugging and assembling process, and meanwhile, after the assembling is finished, the formed liquid level detection device is not afraid of great vibration in the using process and the problem of magnetization of the magnetic induction element cannot occur.
Preferably, the circuit board assembly further comprises a sealing sleeve, the sealing sleeve is of a strip-shaped structure made of insulating materials, the sealing sleeve is arranged on the outer side of each substrate and tightly covers each substrate to prevent the substrates from being separated, and the sealing sleeve is used for packaging the circuit board assembly and has the functions of moisture prevention, mildew prevention, oxidation resistance and insulation on a shell.
Preferably, the magnetic induction elements are sequentially arranged and uniformly fixed on the first substrate, and a circuit for connecting the magnetic induction elements is arranged on the first substrate;
preferably, a plurality of shearing connection points are uniformly arranged on the first substrate, and are used for shearing the first substrate to shorten the length of the first substrate or connecting the shearing connection points of other first substrates to prolong the length of the first substrate;
in the scheme, the shearing connection points are arranged, so that the first substrate is saved, and waste is reduced.
Preferably, the lines include a zero line, a live line and a signal line, and the three lines are respectively and correspondingly provided with welding spots to form the shearing connection points.
Preferably, three welding points corresponding to the zero line circuit, the live line circuit and the signal line circuit are on the same straight line perpendicular to the length direction of the flexible circuit board.
In the above scheme, the three corresponding solder joints of zero line circuit, live wire circuit and signal line circuit three are on the straight line of same perpendicular flexible circuit board length direction, except that convenient processing together, improve work efficiency, still be favorable to in the assembling process to tailor flexible circuit board, can tailor the broken end that has formed the parallel and level, be favorable to the later stage to weld and continue long.
Preferably, the shearing connection point comprises a plurality of shearing connection points which are uniformly distributed on the flexible circuit board.
In the above solution, the shear connection point is disposed between two adjacent magnetic induction elements, and preferably, the shear connection point is disposed at a position intermediate between two adjacent magnetic induction elements. The density of the shearing connection points is set without influencing the precision of the shearing of the substrate, for example, the shearing connection points and the magnetic induction elements can be arranged at intervals, so that the aim of reducing waste can be achieved. Of course, a shear connection point may be provided between each of the plurality of magnetic induction elements, which reduces the burden of substrate production.
Another object of the present invention is to provide a method for mounting a circuit board assembly applied to the above liquid level detection apparatus, comprising the steps of:
s1, cutting the first substrate with the required length according to the process requirement;
s2, cutting a second substrate with a proper length according to the length of the first substrate;
s3, bonding and fixing the first substrate and the second substrate through the third substrate;
and S4, sleeving a sealing sleeve on each fixed substrate for packaging.
In step S1, the length of the first substrate is cut to the length required by the liquid level inspection apparatus.
Preferably, in step S2, the second substrate is cut longer than the first substrate, and a reserved section is formed at one end of the second substrate for later fixing with a corresponding mounting structure to define the position of the circuit board assembly.
In the above scheme, no circuit is arranged on the second substrate, the second substrate has the function of fixing the whole circuit board assembly, the circuit board assembly is fixed on the corresponding mounting structure, and when the second substrate is a nonmagnetic metal plate, the circuit board assembly can be connected on the corresponding mounting structure in a welding mode or a punching mode through screws so as to play a role in fixing.
Preferably, the step S1 is preceded by a process of bonding one surface of the third substrate to the first substrate, and the other surface of the third substrate is protected by a release paper;
preferably, in step S1, the method further includes soldering a sensor lead to one end of the first substrate; on the other hand, between step S1 and step S2, there is further included the step of: s12, detecting a circuit; the circuit detection comprises the steps of checking whether the welding defects such as element insufficient welding, missing welding and the like exist, if so, repair welding is needed, the problem that the circuit of the whole circuit board assembly is found after the circuit board assembly is installed can be prevented through the step, the problem that the repair is troublesome and complex is caused, the first substrate needs to be detached again, and more working time is wasted.
Preferably, in step S3, the method includes fixing the end opposite to the lead end of the first substrate and the end of the second substrate, or fixing the end opposite to the lead end of the first substrate on the surface of the second substrate near the end of the second substrate, and then gradually peeling off the release paper to bond the third substrate to the second substrate.
The steps are simple to operate and good in fixing effect.
Preferably, in step S4, cutting a sealing sleeve having a length between the first substrate and the second substrate, sleeving the sealing sleeve on each substrate, and performing thermal shrinkage sealing on one end of the sealing sleeve away from the lead end, where the other end of the sealing sleeve covers the lead structure on the first substrate, so as to form a protection portion for preventing the lead from being separated due to stress;
in the above scheme, through the lead structure with on the first base plate of sealing sleeve cladding to prevented that the lead wire atress from coming off or causing contact failure's problem, and this sealing sleeve has the effect with each lead wire location, made things convenient for the connection operation in later stage.
Preferably, the heat-shrinkable sealing of the end of the sealing sleeve far away from the lead end comprises the following steps:
s401, sleeving sealing sleeves on the peripheries of the substrates, and reserving an extra-length section at one end, far away from the lead, of the second substrate;
s402, performing thermal shrinkage treatment on one end of the sealing sleeve with the surplus length section;
s403, folding back the surplus length section to be attached to the surface of the second substrate, and sleeving a section of heat-shrinkable tube on the periphery of the folding-back structure;
s404, performing thermal shrinkage treatment on the thermal shrinkage pipe to enable the thermal shrinkage pipe to be tightly retracted and fixed at the inflection structure of the sealing sleeve, so that fixed sealing is realized.
Through the steps, one end of the sealing sleeve far away from the lead end can be completely sealed, liquid is effectively prevented from entering the sealing sleeve from the end, and on the other hand, through the processing method, a larger structure is formed at the end part of the circuit board assembly, so that the circuit board assembly is favorably fixed with a mounting component at the later stage.
After the technical scheme is adopted, compared with the prior art, the invention has the following beneficial effects.
1. According to the invention, the magnetic induction element is fixed on the flexible circuit board, and the flexible circuit board is provided with the shearing connection points with higher density.
2. In the invention, a sealing sleeve is also sleeved outside the detection circuit consisting of the flexible circuit board and the magnetic induction element to form a strip-shaped packaging structure, and the sealing sleeve has the functions of moisture resistance, mildew resistance, oxidation resistance and insulation on a shell.
3. In the invention, the magnetic induction element adopts the tunnel magneto-resistance sensor or the Hall element, so that the welding is convenient, and compared with the existing reed switch, the tunnel magneto-resistance sensor or the Hall element is welded with the flexible circuit board without pin forming and breaking, therefore, the large-scale mechanical production can be realized in batch, and a large amount of labor force is saved. The liquid level detection device has the advantages that the problem of breakage of a magnetic induction element cannot occur in the process of debugging and assembling the liquid level detection device, the sensor cannot be broken even if the assembled finished product falls off in the transportation and moving processes, the sensor cannot be magnetized due to the fact that the assembled finished product is not afraid of huge vibration in the using process, and the reliability and stability of the assembled finished product are improved by 4 ten thousand times compared with those of the conventional reed switch. In summary, the flexible circuit board is used as the substrate of the magnetic induction element, and the sealing sleeve is sleeved outside the flexible circuit board, so that a strip-shaped packaging structure is formed. The structure has reasonable design, and has a plurality of beneficial effects in later period, namely assembly, transportation and use.
4. According to the invention, the tensile strength of the sensor is improved by arranging the second substrate, so that the sensor is convenient to mount and debug, and the expansion coefficient of the second substrate is preferably equal to that of the first substrate, so that the stress of the first substrate is favorably shared, and the first substrate is prevented from being damaged due to stress.
5. According to the invention, the third substrate made of the elastic material is arranged, the third substrate has a buffering effect, and when the first substrate and the second substrate are deformed by an external force, the third substrate can absorb the deformation stress of the first substrate and the second substrate, so that the stress of the first substrate and the second substrate can be coordinated, and the first substrate is prevented from being damaged by the external force independently borne.
6. According to the invention, the first substrate and the second substrate are connected and fixed through the third substrate with the bonding structures on two surfaces, the method is simple, convenient and high in efficiency, and the circuit board assembly formed by installation is stable and reliable. In addition, the third substrate and the first substrate are bonded and fixed in advance, and then the third substrate and the second substrate are bonded and fixed, so that the mounting efficiency is improved.
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention to the right. It is obvious that the drawings in the following description are only some embodiments, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:
FIG. 1 is a schematic view of a first substrate;
FIG. 2 is another view from FIG. 1;
FIG. 3 is a schematic structural view of a circuit board assembly of the present invention;
fig. 4 is a schematic top view of fig. 3.
In the figure: 1. a first substrate; 2. a second substrate; 3. a third substrate; 4. a magnetic induction element; 5. shearing the connecting points; 6. the sleeve is sealed.
It should be noted that the drawings and the description are not intended to limit the scope of the inventive concept in any way, but to illustrate it by a person skilled in the art with reference to specific embodiments.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example one
Referring to fig. 1 to 4, the present embodiment provides a circuit board assembly of a liquid level detection device, including a magnetic induction element 4, a first substrate 1, and a second substrate 2, where the first substrate 1 is a flexible substrate, and the magnetic induction element 4 is disposed on the first substrate 1; the second substrate 2 is a non-magnetic substrate, the hardness of the second substrate is greater than that of the first substrate 1, and the first substrate 1 is fixed on the second substrate 2.
In the scheme, the magnetic induction element 4 is arranged on the flexible substrate, so that winding storage is facilitated, later-stage assembly is facilitated, the second substrate 2 with hardness larger than that of the first substrate 1 is provided, the tensile strength of the sensor is improved by the second substrate 2, and installation and debugging of the circuit board assembly are facilitated.
Preferably, the second substrate 2 is a non-magnetic metal substrate (with an insulating protective layer) or a non-metal substrate, such as a stainless steel plate or an aluminum plate. Preferably, when the second substrate 2 is a metal substrate, in order to prevent interference with the circuit, an insulating protection layer is further disposed on the second substrate 2.
Preferably, the first substrate 1 and the second substrate 2 are both strip-shaped structures, one surface of the first substrate 1 is fixed with the magnetic induction element 4, and the other surface is directly fixed on the second substrate 2 or fixed on the second substrate 2 through a connecting structure;
preferably, the length of the first substrate 1 is smaller than the length of the second substrate 2;
preferably, the width of the first substrate 1 is not greater than the width of the second substrate 2;
in the above solution, the width of the first substrate 1 is not greater than the width of the second substrate 2, which is beneficial for the first substrate 1 to be fixed on the second substrate 2, and is beneficial for the second substrate 2 to protect the first substrate 1, and is also beneficial for the first substrate 1 to be fixed on the second substrate 2.
Preferably, the second substrate 2 has the same coefficient of expansion and contraction as the first substrate 1.
In the above solution, setting the expansion coefficient of the second substrate 2 to be the same as that of the first substrate 1 is beneficial for the second substrate 2 to protect the first substrate 1, and shares the stress with the first substrate 1, for example: when the expansion coefficient of the second substrate 2 is greater than that of the first substrate 1, in an application scene with a hot environment, the second substrate 2 is seriously deformed by heat, the first substrate 1 is less deformed, but the first substrate 1 is fixed on the second substrate 2, and the first substrate 1 can be subjected to tensile force when the second substrate 2 is deformed, so that the second substrate is easily damaged, the service life of the first substrate 1 is shortened, and the application field of the circuit board assembly is limited. When the expansion coefficients of the second substrate 2 and the first substrate 1 are the same, the first substrate 1 and the second substrate 2 deform synchronously in the same environment, thereby preventing the first substrate 1 from being damaged by stress. It should be noted that the coefficient of expansion and contraction referred to in the present invention means: the rate of change of the dimensions of the material in different environments. Wherein the external environment comprises an environmental temperature value and/or a stress condition of the material. Proportion, when this circuit board subassembly that will convolute is stretched, then because the elongation of second base plate 2 equals first base plate 1 to when this circuit board subassembly received the tensile force, first base plate 1 and second base plate 2 atress simultaneously, synchronous deformation share the pulling force jointly, thereby prevented that first base plate 1 is impaired.
Preferably, the circuit board assembly of the liquid level detection device further includes a third substrate 3, the third substrate 3 is made of an elastic material, and the first substrate 1 is fixed on the second substrate 2 through the third substrate 3;
preferably, the third substrate 3 is a buffer substrate for absorbing the deformation stress of the first substrate 1 and/or the second substrate 2;
in the above solution, since the third substrate 3 is made of an elastic material, and thus has a buffering function, when the first substrate 1 and the second substrate 2 are deformed by an external force, the third substrate 3 can absorb the deformation stress of the first substrate 1 and the second substrate 2, so as to coordinate the stress of the first substrate 1 and the second substrate 2, and prevent the first substrate 1 from being damaged by the external force alone, for example, in the process of mounting the circuit board assembly, the first substrate 1 and the second substrate 2 need to be straightened, when the first substrate 1 and the second substrate 2 are unevenly stressed, particularly when the first substrate 1 is stressed, the third substrate 3 located between the first substrate 1 and the second substrate 2 may play a role of buffering, so as to transfer the stressed portion of the first substrate 1 to the second substrate 2, and share the stress of the first substrate 1 through the second substrate 2 to protect the first substrate 1.
Preferably, the thickness of the third substrate 3 is greater than the first substrate 1 and the second substrate 2, and more preferably, the ratio of the thicknesses of the first substrate 1, the second substrate 2, and the third substrate 3 is 1: (1-5): (1-15);
preferably, in the above solution, since the third substrate 3 needs to provide a buffering force, and has a certain requirement on the thickness thereof, the inventor finds, through a great deal of experiments, that in the process of assembling the circuit board assembly at ordinary times, when the thickness of the third substrate 3 is within a certain range, a good buffering effect can be achieved, where the range is: the ratio of the thicknesses of the first substrate 1, the second substrate 2, and the third substrate 3 is 1: (1-5): (1-15).
Preferably, both surfaces of the third substrate 3 are configured to be bondable, one surface is used for being bonded and fixed with the first substrate 1, and the other surface is used for being bonded and fixed with the second substrate 2;
in the scheme, the substrates are connected and fixed in an adhesion mode, and the method is simple, stable and low in cost.
Preferably, the heat-resistant temperature range of the third substrate 3 is-40 ° to 200 °;
in the above solution, because the circuit board assembly is applied in a complicated situation and different external environments, the circuit board assembly may be used in a high temperature environment or a low temperature environment, and therefore, the heat-resistant temperature of the third substrate 3 needs to meet the above requirements to support the circuit board assembly to be applied in various fields.
Preferably, the third substrate 3 is a double-sided adhesive tape;
preferably, the first substrate 1 is a flexible circuit board, the second substrate 2 is a non-magnetic metal substrate or a non-metal substrate, and the magnetic induction element 4 is a tunnel magneto-resistance sensor or a hall element. In the invention, because the first substrate 1 is a flexible substrate and the existing reed switch is easy to be damaged by stress, the Hall element or the tunnel magneto-resistance sensor is selected as the magnetic induction element 4, and the service life of the tunnel magneto-resistance sensor or the Hall element is forty thousand times of that of the reed switch. According to the invention, the magnetic induction element 4 is a tunnel magneto-resistance sensor or a Hall element, and is more suitable for the flexible circuit board, because the glass tube of the reed switch is fragile and is arranged on the flexible circuit board, the reed switch is easy to shake and collide, and secondly, the reed switch can be wound into a disc-shaped structure when the flexible circuit board is stored, so that the space is saved, and the reed switch is easy to break under the action of external force when the flexible circuit board is bent. And when the Hall element is welded on the flexible circuit board, the welding does not need pin forming, the pin is not broken, the welding is convenient, the mass production can be realized, the labor force is saved, the problem of breaking the magnetic induction element 4 in the debugging and assembling process is solved, and simultaneously, the formed liquid level detection device is not afraid of great vibration in the using process and the problem of magnetizing the magnetic induction element 4 is also solved after the assembling is finished.
Preferably, the circuit board assembly further comprises a sealing sleeve 6, the sealing sleeve 6 is a strip-shaped structure made of an insulating material, the sealing sleeve 6 is arranged on the outer side of each substrate and tightly covers each substrate to prevent the substrates from being separated, and the sealing sleeve 6 is used for packaging the circuit board assembly and has the functions of moisture resistance, mildew resistance, oxidation resistance and insulation on a shell.
Preferably, the magnetic induction elements 4 are sequentially arranged and uniformly fixed on the first substrate 1, and a circuit connected with the magnetic induction elements 4 is arranged on the first substrate 1;
preferably, a plurality of cutting connection points 5 are uniformly arranged on the first substrate 1, and are used for cutting the first substrate 1 to shorten the length of the first substrate 1 or connecting the cutting connection points 5 of other first substrates 1 to prolong the length of the first substrate 1;
in the above scheme, the shear connection point 5 is arranged, so that the first substrate 1 is saved, and waste is reduced.
Preferably, the lines include a zero line, a live line and a signal line, and the three lines are respectively and correspondingly provided with welding spots to form the shearing connection points 5.
Preferably, three welding points corresponding to the zero line circuit, the live line circuit and the signal line circuit are on the same straight line perpendicular to the length direction of the flexible circuit board.
In the above scheme, the three corresponding solder joints of zero line circuit, live wire circuit and signal line circuit three are on the straight line of same perpendicular flexible circuit board length direction, except that convenient processing together, improve work efficiency, still be favorable to in the assembling process to tailor flexible circuit board, can tailor the broken end that has formed the parallel and level, be favorable to the later stage to weld and continue long.
Preferably, the plurality of shear connection points 5 are uniformly distributed on the flexible circuit board.
In the above solution, the shear connection point 5 is disposed between two adjacent magnetic induction elements 4, and preferably, the shear connection point 5 is disposed at a position between two adjacent magnetic induction elements 4. The density of the shear connection points 5 is set without affecting the precision of shearing the substrate, for example, the shear connection points 5 can be spaced apart from the magnetic induction elements 4, so that the waste can be reduced. Of course, one shear connection point 5 may be provided between each plurality of magnetic induction elements 4, which reduces the burden of substrate production.
Example two
Referring to fig. 1 and 2, in the present embodiment, a first substrate 1 is further described based on the first embodiment, the first substrate 1 is a flexible substrate, and a magnetic induction element 4 is disposed on the first substrate 1.
In the invention, each magnetic induction element 4 is arranged on the first substrate 1, the first substrate 1 has many advantages, the magnetic induction elements 4 are arranged on the first substrate 1, which is beneficial to storage, for example, the first substrate 1 can be wound to form a roll, and a hard printed circuit board is not needed to be used as the substrate of the magnetic induction elements 4 in the prior art, so that the formed detection circuit is inconvenient to store and easy to wear. On the other hand, the first substrate 1 is adopted as a carrier of the magnetic induction element 4 in the present embodiment, which is beneficial to shearing the first substrate 1 during the assembly process. The existing detection circuit formed by the reed pipe is fragile because the reed pipe is provided with a glass pipe, and the welding of the reed pipe needs pin forming, so that the reed pipe is special in structure and cannot be cut.
Preferably, the first substrate 1 is a strip structure, and the plurality of magnetic induction elements 4 are arranged along the length direction of the substrate.
Preferably, the magnetic induction elements 4 are sequentially arranged and uniformly fixed on the substrate.
Preferably, the first substrate 1 is provided with a cutting connection point 5 for cutting the substrate to shorten the substrate length and for connecting another substrate to lengthen the substrate length.
Because the first substrate 1 adopts the flexible circuit board, the material is soft, and the shearing is facilitated compared with the existing hard printed circuit board. Therefore, on the basis that the first substrate 1 is a flexible circuit board, the shearing connection point 5 is further arranged on the first substrate 1, and the extension and the shortening of the first substrate 1 are facilitated.
The plurality of shear connection points 5 are uniformly distributed on the flexible circuit board 1.
Preferably, the liquid level detection device comprises a guide pipe, a magnetic floating body moving along the axial direction of the guide pipe is sleeved outside the guide pipe, and each substrate is arranged in the inner cavity of the guide pipe along the length direction of the guide pipe.
Preferably, the magnetic induction element 4 is a tunneling magneto-resistance sensor or a hall element.
Furthermore, the lead of the first substrate 1 is connected with an electric control unit, when the magnetic floating body floats up and down and acts on a certain magnetic induction element 4, the magnetic induction element 4 generates a potential difference, the electric control unit detects and analyzes the potential difference of each magnetic induction element 4, detected liquid level result information is displayed to a user through a display, and meanwhile, 4-20 mA two-wire current signals or RS-485 communication is output to remotely transmit the liquid level signals to other electronic equipment.
EXAMPLE III
The embodiment provides an installation method of a circuit board assembly applied to the liquid level detection device in the first embodiment, which comprises the following steps:
s1, cutting the first substrate 1 with the required length according to the process requirement;
s2, cutting the second substrate 2 with the proper length according to the length of the first substrate 1;
s3, the first substrate 1 and the second substrate 2 are fixedly bonded through the third substrate 3;
s4, sealing sleeves 6 are fitted over the substrates fixed integrally to seal them.
In step S1, the length of the first substrate 1 is cut to the length required by the liquid level inspection apparatus.
Preferably, in step S2, the second substrate 2 is cut to be longer than the first substrate 1, and a reserved section is formed at one end thereof for later fixing with a corresponding mounting structure to define the position of the circuit board assembly.
In the above scheme, no circuit is arranged on the second substrate 2, the second substrate 2 also has the function of fixing the whole circuit board assembly, the circuit board assembly is fixed on the corresponding mounting structure, and when the second substrate 2 is a metal plate (stainless steel or aluminum plate, etc.), the circuit board assembly can be connected on the corresponding mounting structure in a welding mode or a punching and screw fixing mode to play a role in fixing.
Preferably, the step S1 is preceded by a process of bonding one surface of the third substrate 3 to the first substrate 1, and the other surface of the third substrate 3 is protected by a release paper;
preferably, in step S1, the method further includes soldering a sensor lead to one end of the first substrate 1; on the other hand, between step S1 and step S2, there is further included the step of: s12, detecting a circuit; the circuit detection comprises checking whether the welding defects such as element insufficient welding, missing welding and the like exist, if so, repair welding is needed, the problem that the circuit is found after the whole circuit board assembly is installed can be prevented through the step, the problem that the repair is troublesome and complicated is caused, the first substrate 1 needs to be detached again, and more working time is wasted.
Preferably, in step S3, the method includes fixing the end opposite to the lead terminal of the first substrate 1 and the end of the second substrate 2, or fixing the end opposite to the lead terminal of the first substrate 1 on the surface of the second substrate 2 near the end of the second substrate, and then gradually peeling off the release paper to bond the third substrate 3 on the second substrate 2.
The steps are simple to operate and good in fixing effect.
Preferably, in step S4, the method includes cutting the sealing sleeve 6 with a length between the first substrate 1 and the second substrate 2, sleeving the sealing sleeve 6 on each substrate, and thermally shrinking and sealing one end of the sealing sleeve away from the lead end, where the other end of the sealing sleeve 6 covers the lead structure on the first substrate 1, so as to form a protection portion for preventing the lead from being separated by a force;
in the above scheme, the lead structure on the first substrate 1 is coated by the sealing sleeve 6, so that the problem that the lead falls off or is in poor contact due to stress is prevented, the sealing sleeve 6 has the function of positioning each lead, and the later-stage connection operation is facilitated.
Preferably, the heat-shrinking and sealing of the end of the sealing sleeve 6 far away from the lead end comprises the following steps:
s401, sleeving the sealing sleeve 6 on the periphery of each substrate, and reserving an extra-length section at one end of the second substrate 2 far away from the lead;
s402, performing thermal shrinkage treatment on one end of the sealing sleeve 6 with the surplus length section;
s403, folding back the surplus length section to be attached to the surface of the second substrate 2, and sleeving a section of heat-shrinkable tube on the periphery of the folding-back structure;
s404, performing thermal shrinkage treatment on the thermal shrinkage pipe to enable the thermal shrinkage pipe to be tightly retracted and fixed at the folding structure of the sealing sleeve 6, so that fixed sealing is realized.
Through the steps, one end of the sealing sleeve 6, which is far away from the lead end, can be completely sealed, so that liquid is effectively prevented from entering the sealing sleeve 6 from the end, and on the other hand, through the treatment of the method, a larger structure is formed at the end part of the circuit board assembly, so that the circuit board assembly is favorably fixed with a mounting component at the later stage.
Preferably, in step S401, the sealing sleeve 6 is sleeved on the periphery of each substrate, and an auxiliary installation of equipment can be selected according to actual conditions, wherein the diameter of the sealing sleeve 6 is 12mm, and if the first substrate 1 to be cut is long, the diameter of the sealing sleeve 6 is 14mm, and further, the sealing sleeve 6 is made of a transparent thickening material, so that the operation is safe and easy. Preferably, the sealing sleeve 6 is a 125 ℃ temperature-resistant heat-shrinkable insulating environment-friendly flame-retardant sleeve. On the other hand, when the length of each substrate is longer, the sealing sleeve 6 is not easy to be sleeved on each substrate, and then the air pump can be used for supplying air to inflate and bulge the sealing sleeve 6, so that each substrate is conveniently fed into the sealing sleeve 6, and preferably, when the length of each substrate is more than 3 meters, the air pump is used for assisting installation.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (14)
1. A circuit board assembly of a liquid level detection device is characterized by comprising a magnetic induction element, a first substrate, a second substrate and a third substrate, wherein the first substrate is a flexible substrate, and the magnetic induction element is arranged on the first substrate; the second substrate is a nonmagnetic substrate, the hardness of the second substrate is greater than that of the first substrate, the third substrate is a buffer substrate made of elastic materials, the first substrate is fixed on the second substrate through the third substrate, and the width of the first substrate is not greater than that of the second substrate; the expansion coefficient of the second substrate is the same as that of the first substrate, and the thickness of the third substrate is larger than that of the first substrate and the second substrate and is used for absorbing the deformation stress of the first substrate and/or the second substrate; the magnetic induction element is a tunnel magneto-resistance sensor or a Hall element;
the circuit that is provided with on the first base plate and connects each magnetic induction element, the circuit includes zero line circuit, live wire circuit and signal line circuit, and what this three circuit corresponded is provided with the solder joint and forms the shearing tie point, the shearing tie point include a plurality ofly, evenly distributed is on first base plate, wherein, the three solder joint that corresponds on the three circuit is on the straight line of same perpendicular first base plate length direction.
2. The circuit board assembly of the liquid level detection device according to claim 1, wherein the first substrate and the second substrate are both in a strip structure, one surface of the first substrate is fixed with the magnetic induction element, and the other surface of the first substrate is attached to the third substrate; the length of the first substrate is smaller than that of the second substrate.
3. The circuit board assembly of the liquid level detection device according to claim 1 or 2, wherein the ratio of the thicknesses of the first substrate, the second substrate and the third substrate is 1: (1-5): (1-15).
4. The circuit board assembly of the liquid level detection device according to claim 2, wherein both surfaces of the third substrate are configured to be adhesive, one surface is used for being adhered and fixed with the first substrate, and the other surface is used for being adhered and fixed with the second substrate.
5. The circuit board assembly of claim 4, wherein the third substrate has a heat-resistant temperature range of-40 ° to 200 °.
6. The circuit board assembly of claim 4, wherein the first substrate is a flexible circuit board, and the second substrate is a non-magnetic metal substrate or a non-metal substrate.
7. The circuit board assembly of the liquid level detection device according to claim 1 or 2, further comprising a sealing sleeve, wherein the sealing sleeve is a heat shrinkable tube made of an insulating material, and the sealing sleeve is sleeved outside each substrate to tightly cover each substrate to prevent the substrates from being separated.
8. A method of mounting a circuit board assembly for use in a fluid level sensing device according to any one of claims 1 to 7, comprising the steps of:
s1, cutting the first substrate with the required length according to the process requirement;
s2, cutting a second substrate with a proper length according to the length of the first substrate;
s3, bonding and fixing the first substrate and the second substrate through the third substrate;
and S4, sleeving a sealing sleeve on each fixed substrate for packaging.
9. The mounting method according to claim 8, wherein in step S2, the second substrate is cut longer than the first substrate, and a reserved section is formed at one end thereof for later fixing with a corresponding mounting structure to define the position of the circuit board assembly.
10. The mounting method according to claim 8 or 9, wherein the step S1 is preceded by a step of bonding one surface of the third substrate to the first substrate, and the other surface of the third substrate is protected by a release paper.
11. The mounting method according to claim 10, further comprising soldering a sensor lead to one end of the first substrate in step S1.
12. The mounting method according to claim 10, wherein step S3 comprises fixing the end opposite to the lead terminal of the first substrate to the end of the second substrate, or fixing the end opposite to the lead terminal of the first substrate to a position on the surface of the second substrate near the end of the second substrate, and then gradually peeling off the release paper to bond the third substrate to the second substrate.
13. The mounting method according to claim 8, wherein in step S4, the method includes cutting a sealing sleeve having a length between the first substrate and the second substrate, sleeving the sealing sleeve on each substrate, and heat-shrinking an end of the sealing sleeve away from the lead ends to seal the end, and the other end of the sealing sleeve covers the lead structure on the first substrate to form a protection portion for preventing the lead from being detached by force.
14. The method of mounting of claim 13, wherein heat shrink sealing an end of the sealing sleeve distal to the lead end comprises the steps of:
s401, sleeving sealing sleeves on the peripheries of the substrates, and reserving an extra-length section at one end, far away from the lead, of the second substrate;
s402, performing thermal shrinkage treatment on one end of the sealing sleeve with the surplus length section;
s403, folding back the surplus length section to be attached to the surface of the second substrate, and sleeving a section of heat-shrinkable tube on the periphery of the folding-back structure;
s404, performing thermal shrinkage treatment on the thermal shrinkage pipe to enable the thermal shrinkage pipe to be tightly retracted and fixed at the inflection structure of the sealing sleeve, so that fixed sealing is realized.
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| CN110061399B (en) * | 2019-05-21 | 2020-07-07 | 中电科芜湖钻石飞机制造有限公司 | General airplane component wire harness crimping method |
| CN110196090A (en) * | 2019-06-28 | 2019-09-03 | 安徽络嵌控制系统有限公司 | A kind of accommodating device and liquid level sensor |
| CN113701615A (en) * | 2021-08-23 | 2021-11-26 | 上海米尔圣传感器有限公司 | Position sensor and position detection device |
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