Tinning method of strain gauge and strain gauge

Abstract

The embodiment of the invention relates to the technical field of tin soldering, and discloses a tinning method for a strain gauge, and the method comprises the steps: providing the strain gauge; providing welding equipment, and heating the welding equipment to a preset temperature; providing a soldering tin material, and melting the soldering tin material at the welding equipment; providing a positioning jig, and fixing the strain gauge on the positioning jig; tinning is conducted on the strain gauges on the positioning jig through the welding equipment; and the strain gauge is cleaned. By means of the mode, the stable tinning effect can be achieved without manual experience, and the problems that traditional manual soldering iron welding is low in efficiency and poor in tinning quality consistency are solved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of soldering technology, and in particular to a method for soldering a strain gauge and a strain gauge. Background Art

[0002] Strain gauges work by converting mechanical strain into electrical signals. The core component is the sensitive grid. In order to ensure a good electrical connection between the sensitive grid and the lead, it is usually necessary to tin the lead welding part. Tinning can ensure that the current flows smoothly between the sensitive grid and the lead, avoiding measurement errors caused by poor contact. In addition, tinning can prevent oxidation between the lead and the sensitive grid, forming a protective film between the lead and the sensitive grid, protecting the welding part from environmental influences, thereby extending the service life of the strain gauge.

[0003] In the process of implementing the embodiments of the present application, the inventors found that: at present, the commonly used tinning methods for strain gauges mainly include manual soldering and spot welding. Manual soldering has problems such as low efficiency and poor consistency of tinning quality. Spot welding has a limited scope of application and has a poor effect on materials with large thickness differences. Summary of the invention

[0004] The main technical problem solved by the embodiments of the present application is to provide a method for tinning a strain gauge. Tinning is performed by welding equipment in conjunction with a positioning fixture, and a stable tinning effect can be achieved without manual experience, thereby overcoming the problems of low efficiency and poor consistency in tinning quality in traditional manual soldering with a soldering iron.

[0005] In order to solve the above technical problems, a technical solution adopted in an embodiment of the present application is: to provide a method for tinning a strain gauge, including providing a strain gauge; providing a welding device, and heating the welding device to a preset temperature; providing a solder material, and melting the solder material at the welding device; providing a positioning jig, and fixing the strain gauge on the positioning jig; using the welding device to tin the strain gauge on the positioning jig; and cleaning the strain gauge.

[0006] Optionally, the welding device includes a heating end, and the step of melting the solder material at the welding device further includes: heating the heating end to a preset temperature; and controlling the solder material to melt at the heating end to form a droplet.

[0007] Optionally, the strain gauge includes a welding area, and the step of using a welding device to tin the strain gauge on the positioning fixture further includes: controlling the heating end to be positioned in the welding area; making the droplet-shaped solder material of the heating end contact the welding area; and controlling the droplet-shaped solder material of the heating end to roll in the welding area.

[0008] Optionally, the positioning jig is provided with a plurality of fixed positions, and the step of fixing the strain gauge to the positioning jig further comprises: fixing the plurality of strain gauges to the plurality of fixed positions respectively; providing a tinning platform, and placing the positioning jig on the tinning platform.

[0009] Optionally, the step of cleaning the strain gauge further includes: providing a cleaning device, wherein anhydrous ethanol is provided in the cleaning device; placing the strain gauge in the anhydrous ethanol; and cleaning the strain gauge.

[0010] Optionally, the method further comprises: detecting the height of the solder material on the strain gauge; judging whether the height of the solder material is within a preset height range; if so, determining that the soldering is qualified;

[0011] Optionally, the method further includes: if it is determined that the tinning is unqualified, adjusting the rolling times of the welding equipment, and returning to the step of using the welding equipment to tin the strain gauge on the positioning fixture.

[0012] Optionally, it is characterized in that the heating end includes a working end, and before the step of melting the solder material at the welding device, it also includes: using a cleaning agent to clean the oxide layer of the working end.

[0013] Optionally, the solder material is lead-free solder wire.

[0014] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present application is: to provide a strain gauge, wherein the strain gauge is prepared by using any of the above strain gauge tinning methods.

[0015] The embodiment of the present application provides a method for tinning a strain gauge, including providing a strain gauge, providing a welding device, heating the welding device to a preset temperature, providing a solder material, melting the solder material at the welding device, providing a positioning jig, fixing the strain gauge on the positioning jig, using the welding device to tin the strain gauge on the positioning jig, and finally cleaning the strain gauge. The welding device is used in conjunction with the positioning jig for tinning, and a stable tinning effect can be achieved without manual experience, overcoming the problems of low efficiency and poor consistency of tinning quality in traditional manual soldering iron welding. At the same time, the method significantly improves production efficiency by simultaneously fixing multiple strain gauges on the positioning jig for batch tinning operations. In addition, the tinning method of the present invention achieves precise tinning through the rolling operation of the welding device, which solves the problem that it is difficult to control the tinning height on small-sized pads in traditional spot welding, and ensures the stability and controllability of the tinning quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the prior art description. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0017] Figure 1 This is a flow chart of a tinning method for a strain gauge according to an embodiment of the present application;

[0018] Figure 2 is a further flow chart of step S103;

[0019] Figure 3 is a further flow chart of step S104;

[0020] Figure 4 is a further flow chart of step S105;

[0021] Figure 5 is a further flow chart of step S106;

[0022] Figure 6 This is another flow chart of a tinning method for a strain gauge according to an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "vertical", "horizontal", etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0024] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0025] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0026] See also Figure 1 , Figure 1 The present invention is a flowchart of a method for tinning a strain gauge according to an embodiment of the present invention. The method comprises the following steps:

[0027] Step S101: providing a strain gauge;

[0028] First, the required strain gauge is provided. The strain gauge includes a sensitive grid and a lead wire, and a welding area is provided at the connection between the lead wire and the sensitive grid. The welding area needs to be tinned to ensure good electrical connection.

[0029] Step S102: providing a welding device, and heating the welding device to a preset temperature;

[0030] Tinning requires high temperature to melt the tin wire so that it adheres to the pad. The heating function of the soldering equipment provides the necessary heat source. The preset temperature is set according to the melting point of the solder material to ensure that the solder material can melt at a suitable temperature, but not too high to cause the solder material to evaporate or oxidize. This embodiment uses an automatic soldering machine as the soldering equipment.

[0031] Step S103: providing solder material, and melting the solder material at the welding equipment;

[0032] In the embodiment of the present application, the solder material is lead-free tin wire.

[0033] Lead-free solder that complies with the RoHS standard is selected, and its composition is usually Sn-Ag-Cu alloy. The diameter of the solder material should match the size of the strain gauge pad. In the embodiment of the present application, a solder wire with a specification of 0.5-0.8 mm is used.

[0034] Lead-free solder wire has good wettability, ensuring a reliable metal connection with the pad surface, excellent mechanical strength, good solder joint fatigue resistance and appropriate fluidity, making it easy to control the amount and shape of soldering, and the melting point range of lead-free solder wire is moderate.

[0035] Select lead-free solder material and feed it into the soldering equipment that has reached the preset temperature. Under the heating state of the soldering equipment, the solder material begins to melt, and through precise control, the molten solder forms a drop-like structure hanging on the soldering equipment.

[0036] See also Figure 2 In the embodiment of the present application, the welding device includes a heating end, and step S103 further includes:

[0037] Step S131: heating the heating end to a preset temperature;

[0038] In the embodiment of the present application, an automatic welding machine is used as the welding equipment. The main component of the welding equipment is a heating end with a heating function, which heats the heating end to a preset temperature of 340°C. At this temperature, the lead-free solder material can achieve ideal fluidity, ensuring that the solder can fully melt and form a stable droplet structure. At the same time, this temperature will not cause thermal damage to the sensitive grid and base material of the strain gauge. Too low a temperature will result in insufficient solder fluidity and affect the quality of tinning; too high a temperature may damage the strain gauge or cause the solder to oxidize too quickly.

[0039] Step S132: controlling the solder material to melt at the heating end to form droplets.

[0040] Controlling the molten solder material into droplets can easily control the amount of tin applied and achieve precise tinning. The size of the tin droplets determines the amount of tin applied. By controlling the size of the tin droplets, the amount of tin applied can be accurately controlled to avoid excessive or insufficient tinning.

[0041] In an embodiment of the present application, the heating end includes a working end, and before the step of melting the solder material at the welding device, it also includes: using a cleaning agent to clean the oxide layer of the working end.

[0042] Before cleaning, the working end needs to be fully inspected to confirm its surface condition and degree of oxidation. A professional cleaning agent should be selected, which should have good ability to remove oxides and will not corrode the material of the working end.

[0043] First, heat the heating end to a suitable temperature, which should be lower than the normal operating temperature and usually controlled within the range of 200-250°C. Then, use a special cleaning tool impregnated with a cleaning agent to carefully wipe the surface of the working end. The cleaning process must ensure that the oxide layer is completely removed to reveal the original color of the metal.

[0044] Step S104: providing a positioning jig, and fixing the strain gauge on the positioning jig;

[0045] The positioning fixture can fix the strain gauge to avoid displacement during the tinning process, thereby ensuring the accuracy of the tinning position. The positioning fixture can also accurately locate the position of the soldering pad to ensure that the solder material can accurately drip onto the soldering pad.

[0046] In the embodiment of the present application, the positioning fixture needs to be designed according to the shape and size of the strain gauge to ensure that the strain gauge can be accurately fixed.

[0047] See also Figure 3 In the embodiment of the present application, the positioning fixture is provided with a plurality of fixed positions, and step S104 further comprises:

[0048] Step S141: fixing the plurality of strain gauges at the plurality of fixed positions respectively;

[0049] It should be noted that multiple fixed positions are set on the jig, and the size and shape of each fixed position are completely matched with the strain gauge. The fixed position adopts a precise positioning structure to ensure the placement accuracy of the strain gauge. In the embodiment of the present application, the fixing method adopts a clamping structure that can be quickly loaded and unloaded, which is convenient for batch operation. The jig material is made of high temperature resistant material to ensure dimensional stability during the welding process.

[0050] Step S142: Provide a tinning platform and place the positioning fixture on the tinning platform.

[0051] Place the positioning fixture at the designated position on the tinning platform, then fix multiple strain gauges on the fixture in sequence according to the preset positions, and finally use the positioning pins to ensure the accurate position of the fixture on the tinning platform.

[0052] Step S105: using the welding equipment to tin the strain gauge on the positioning fixture;

[0053] The molten solder material (tin droplets) is transferred to the pad to achieve electrical connection, and then by controlling the number of tin droplets and the moving trajectory of the welding equipment, the welding equipment moves according to the trajectory designed by the program and drops the tin droplets on the pad, the height of the tin can be controlled.

[0054] In the embodiment of the present application, the single tinning time is about 5 seconds. This time parameter is the best balance point found between efficiency and quality. The 5-second operation time is enough for the solder to fully contact the pad and form a reliable welding connection while maintaining high production efficiency. This time parameter also takes into account the need for heat transfer, ensuring that the welding area can obtain enough heat to achieve good welding, and will not affect other parts of the strain gauge due to excessive heating time.

[0055] See also Figure 4 In the embodiment of the present application, the strain gauge includes a welding area, and step S105 further includes:

[0056] Step S151: controlling the heating end to be positioned in the welding area;

[0057] Control the heating end of the welding equipment so that it is precisely positioned over the welding area of ​​the strain gauge.

[0058] Step S152: making the drip solder material at the heating end contact the welding area;

[0059] The solder drop on the heating end is brought into contact with the welding area. At this time, the contact force needs to be controlled to ensure sufficient contact without causing damage to the strain gauge.

[0060] Step S153: controlling the droplet-shaped solder material at the heating end to roll in the welding area.

[0061] According to the pre-set program, the heating end is controlled to drive the droplet of solder to roll in the welding area. The rolling process utilizes the different adhesion characteristics of solder to different material surfaces, which can achieve precise adhesion of solder to the pad position.

[0062] In the embodiment of the present application, in a single tinning operation, by controlling the number of rolling times and pressure, the solder height control of 0.08-0.1 mm is achieved. The standard deviation of high consistency is controlled within the range of ±0.02 mm. This precise size control ensures that the measurement accuracy of the strain gauge will not be affected by the welding process. In particular, the application on small-sized pads (1.0×0.3 mm) shows significant process advantages.

[0063] In the embodiment of the present application, precise tinning is achieved by using the principle of difference in surface adhesion of solder materials without pencil welding wires, and precise tinning of the pad position is achieved by using the difference in adhesion of molten tin droplets to different materials at the substrate and pad position.

[0064] In the embodiment of the present application, by controlling the positioning of the heating end in the welding area, making the droplet-shaped solder material of the heating end contact with the welding area, and controlling the droplet-shaped solder material of the heating end to roll in the welding area, the tinning quality can be stable, the solder is evenly distributed, and the tinning height can be controlled, which meets the requirements of precision strain gauges, solves the problems of low efficiency and unstable quality of traditional manual tinning, and overcomes the limitations of spot welding on small-sized pads.

[0065] Step S106: Cleaning the strain gauge.

[0066] It should be noted that during the cleaning process, it is necessary to ensure that the strain gauge is completely immersed in the cleaning liquid.

[0067] See also Figure 5 , step S106 further includes:

[0068] Step S161: providing a cleaning device, wherein anhydrous ethanol is provided in the cleaning device;

[0069] In this application, anhydrous ethanol is selected as the cleaning medium. This selection is based on the following considerations: first, anhydrous ethanol has excellent solubility and can effectively dissolve and remove residual flux and other organic pollutants in the welding process. Second, anhydrous ethanol is highly volatile and can dry quickly after cleaning without leaving residue on the surface of the strain gauge. In addition, anhydrous ethanol has good compatibility with various materials of strain gauges and will not cause corrosion or other adverse effects.

[0070] Step S162: placing the strain gauge in the anhydrous ethanol;

[0071] Step S163: Cleaning the strain gauge.

[0072] In the embodiment of the present application, the sample strain gauge with good tinning is placed in a cleaning device filled with anhydrous ethanol, and ultrasonic cleaning is performed for 10 minutes to remove the residual flux on the surface to obtain a good tinning product. During the experiment, in the first 5 minutes, the ultrasonic energy can effectively loosen and peel off the surface contaminants, and the last 5 minutes ensure that the deep residues are fully removed, and also provide enough time for the full replacement of the cleaning liquid. Although extending the cleaning time may further improve the cleanliness, it may affect production efficiency, and the improvement of the cleaning effect is not significant.

[0073] In some embodiments, the cleaning temperature can be maintained within the room temperature range of 20-25°C. Within this temperature range, anhydrous ethanol can maintain good solubility and will not volatilize faster due to excessively high temperatures. At the same time, cleaning at room temperature also avoids the potential impact of temperature stress on the strain gauge. If the temperature is too high, the cleaning agent may volatilize too quickly, affecting the cleaning effect; if the temperature is too low, the cleaning efficiency will be reduced.

[0074] The embodiment of the present application provides a method for tinning a strain gauge, including providing a strain gauge, providing a welding device, heating the welding device to a preset temperature, providing a solder material, melting the solder material at the welding device, providing a positioning jig, fixing the strain gauge on the positioning jig, using the welding device to tin the strain gauge on the positioning jig, and finally cleaning the strain gauge. The welding device is used in conjunction with the positioning jig for tinning, and a stable tinning effect can be achieved without manual experience, overcoming the problems of low efficiency and poor consistency of tinning quality in traditional manual soldering iron welding. At the same time, the method significantly improves production efficiency by simultaneously fixing multiple strain gauges on the positioning jig for batch tinning operations. In addition, the tinning method of the present invention achieves precise tinning through the rolling operation of the welding device, which solves the problem that it is difficult to control the tinning height on small-sized pads in traditional spot welding, and ensures the stability and controllability of the tinning quality.

[0075] See also Figure 6 , Figure 6 1 is another flow chart of a tinning method for a strain gauge according to an embodiment of the present invention, the method comprising the following steps:

[0076] Step S107: Detecting the height of the solder material on the strain gauge;

[0077] This solution uses high-precision measuring equipment to detect solder height. The detection process includes: (1) using precision measuring instruments to measure solder height; (2) measuring at multiple locations on each solder joint; (3) recording the measurement data, calculating the average value, and finally generating a report.

[0078] Step S108: determining whether the height of the solder material is within a preset height range;

[0079] The preset height range management sets the qualified standard of soldering height according to the specific requirements of the strain gauge: standard height range: 0.08-0.1 mm; allowable error range: ±0.02 mm.

[0080] The height range of 0.08-0.1 mm is set based on two main considerations: First, this height can ensure that the welding strength meets the requirements of the strain gauge and provides sufficient mechanical connection strength. Second, this height range can ensure a good electrical connection without generating too much solder accumulation to avoid short circuits or affecting the strain characteristics of the strain gauge. Too low a height may lead to unreliable connections, while too high a height may affect product performance and appearance.

[0081] The height control accuracy of ±0.02 is set because: the control accuracy of 0.02 mm ensures that the tinning height fluctuation of each product in mass production is within an acceptable range. This accuracy value takes into account the control capability of the automatic welding equipment, the dimensional characteristics of the strain gauge, and the actual application requirements. By accurately controlling the tinning height, the consistency of product performance can be guaranteed, the yield rate can be improved, and the requirements of high-precision strain measurement can be met.

[0082] Step S109: If yes, then determine that the tinning is qualified;

[0083] By collecting solder height measurement data, and then comparing the measurement results with the preset standards, it is finally determined whether the tinning quality is qualified. The settings of the above parameters are interrelated and together constitute a complete process parameter system. By strictly controlling these parameters, a stable and high-quality strain gauge tinning effect can be achieved, ensuring the reliability and consistency of the product.

[0084] If it is determined that the tinning is unqualified, the rolling times of the welding device are adjusted, and the process returns to the step of using the welding device to tin the strain gauge on the positioning fixture.

[0085] When the tinning height is found to be unqualified during testing, the following adjustment process is initiated: 1. Parameter adjustment: adjust the rolling times of the welding equipment; optimize the rolling speed and pressure; and correct the welding temperature parameters. 2. Verification and confirmation: perform sample strain gauge test; re-check the adjusted soldering height; and confirm the adjustment effect.

[0086] The present application also provides an embodiment of a strain gauge, which is prepared based on the above steps, and the specific implementation methods are not described here one by one.

[0087] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for tinning a strain gauge, characterized in that: include: Provide strain gauges; Providing a welding device, and heating the welding device to a preset temperature; Providing solder material, and melting the solder material at the soldering equipment; Providing a positioning jig, and fixing the strain gauge on the positioning jig; Using the welding equipment to tin the strain gauge on the positioning fixture; The strain gauge is cleaned.

2. The tinning method for strain gauge according to claim 1, characterized in that: The welding device comprises a heating end, and the step of melting the solder material at the welding device further comprises: Raising the temperature of the heating end to a preset temperature; The solder material is controlled to melt at the heating end to form a drop shape.

3. The tinning method of the strain gauge according to claim 2, characterized in that: The strain gauge includes a welding area, and the step of using a welding device to tin the strain gauge on the positioning fixture further includes: Controlling the heating end to be positioned in the welding area; bringing the drip-shaped solder material of the heating end into contact with the welding area; The drop-shaped solder material at the heating end is controlled to roll in the welding area.

4. The tinning method for strain gauge according to claim 1, characterized in that: The positioning fixture is provided with a plurality of fixed positions, and the step of fixing the strain gauge to the positioning fixture further comprises: Fixing the plurality of strain gauges at the plurality of fixed positions respectively; A tinning platform is provided, and the positioning fixture is placed on the tinning platform.

5. The tinning method for strain gauge according to claim 1, characterized in that: The step of cleaning the strain gauge further comprises: Providing a cleaning device, wherein anhydrous ethanol is provided in the cleaning device; placing the strain gauge in the anhydrous ethanol; The strain gauge is cleaned.

6. The tinning method of the strain gauge according to claim 1, characterized in that: The method further comprises: Detecting the height of the solder material on the strain gauge; Determining whether the height of the solder material is within a preset height range; If so, it is determined that the tinning is qualified.

7. The tinning method for strain gauge according to claim 6, characterized in that: The method further comprises: If it is determined that the tinning is unqualified, the rolling times of the welding device are adjusted, and the process returns to the step of using the welding device to tin the strain gauge on the positioning fixture.

8. The tinning method for strain gauge according to claim 2, characterized in that: Features The heating end includes a working end, and before the step of melting the solder material at the welding device, the step further includes: The oxide layer of the working end is cleaned using a cleaning agent.

9. The tinning method for strain gauge according to claim 1, characterized in that: The solder material is lead-free solder wire.

10. A strain gauge, characterized in that: The strain gauge is prepared by the tinning method for strain gauges according to any one of claims 1 to 9.

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