A selective welding equipment liquid level height detection device and method

Abstract

This invention relates to the technical field of solder level detection, and particularly to a solder level height detection device and method for selective soldering equipment. The device includes: a solder pot, comprising a pot body and a pot cover, the pot cover having a recessed observation tube extending from the outside of the pot body to the inside of the pot body; a drive control assembly for driving the solder pot to rotate in the X, Y, and Z axes; a laser sensor for detecting the solder level in the solder pot via the recessed observation tube; and a control module, comprising: a receiving unit for receiving a level detection command and for receiving the detection value from the laser sensor; a control unit for responding to the level detection command by driving the solder pot to a preset coordinate and controlling the laser sensor to perform detection; a judgment unit for judging whether the detection value falls within a preset range; and an alarm unit for issuing an alarm message if the detection value does not fall within the preset range. This application has the effect of improving detection accuracy and equipment compatibility.

Description

Technical Field

[0001] This invention relates to the technical field of solder liquid level detection, and in particular to a device and method for detecting the liquid level height in selective soldering equipment. Background Technology

[0002] In the high-end soldering manufacturing field of PCBs, selective wave soldering technology is widely used due to its efficient and precise soldering results. However, in the selective wave soldering process, the solder level in the pot is a crucial process parameter that directly affects the height of the solder wave and the soldering quality.

[0003] When the liquid level is too low, if the peak height is not corrected, the soldering peaks will decrease, leading to poor soldering and affecting product reliability and stability. If peak height correction is performed, the inverter needs to increase its power to maintain a consistent liquid level when it's low. However, when the liquid level is extremely low, the inverter may not be able to restore the liquid level even at its maximum power, which could damage the inverter and reduce product quality due to poor soldering. Therefore, when the liquid level is too low, manual or automatic soldering devices are usually required to add solder to ensure a smooth soldering process.

[0004] On the other hand, when the solder level is too high, the inverter power also needs to be adjusted to maintain a consistent solder level. However, an excessively high solder level increases the risk of solder overflow, posing a threat to safe production. Therefore, accurate detection and monitoring of the solder pot level is particularly important in selective wave soldering.

[0005] Currently, there are two main methods for detecting the solder pot level in the market: one is the float method, which, while highly accurate, is also relatively expensive and complex to install. Furthermore, different types of wave soldering machines require different models of floats, increasing equipment compatibility and maintenance costs. The second method is the probe method, which uses one or more probes to determine if the solder level has reached a preset position, but this method has lower accuracy and less precision, making it difficult to meet the stringent soldering quality requirements of high-end applications. Summary of the Invention

[0006] To improve detection accuracy and equipment compatibility, this application provides a device and method for detecting the liquid level height of selective welding equipment.

[0007] The above-mentioned objective of this application is achieved through the following technical solution:

[0008] A selective welding equipment liquid level height detection device, comprising:

[0009] A tin furnace, comprising a furnace body and a furnace cover, wherein the furnace cover is provided with a sunken observation tube extending from the outside of the furnace body to the inside of the furnace body;

[0010] Drive control components are used to drive the tin furnace to rotate in the X, Y, and Z axes;

[0011] A laser sensor, which detects the height of molten tin in the tin furnace via a submerged observation tube;

[0012] The control module includes:

[0013] The receiving unit is used to receive liquid level detection commands and to receive detection values ​​from the laser sensor.

[0014] The control unit is used to drive the solder pot to a preset coordinate in response to a liquid level detection command, and to control the laser sensor to perform detection. The preset coordinate corresponds to the physical position of the solder pot where the laser sensor can detect the height of the molten solder in the solder pot through the sinking observation tube.

[0015] The judgment unit is used to determine whether the detected value falls within a preset range;

[0016] An alarm unit is used to issue an alarm message if the detected value does not fall within a preset range.

[0017] In a preferred embodiment, this application can be further configured such that the receiving module is also used to receive a lifetime detection command;

[0018] The control module also includes:

[0019] The molten tin temperature monitoring unit is used to monitor the temperature of the molten tin inside the tin furnace;

[0020] The recording unit is used to record the molten tin temperature to form historical detection data when a liquid level detection command is received; the historical detection data is reset after the laser sensor is replaced.

[0021] In a preferred embodiment, this application can be further configured such that the control module also includes:

[0022] The scrap value calculation unit is used to calculate the scrap value based on the historical detection data, the solder melt temperature curve and the normal operating temperature range of the laser sensor. The solder melt temperature curve is a function of temperature with respect to time.

[0023] If the scrap value reaches the preset value, the alarm unit will issue a replacement prompt.

[0024] In a preferred embodiment, this application can be further configured such that the control module also includes:

[0025] The scrap value calculation unit includes:

[0026] The calculation subunit is used to calculate the first proportional factor m% of the total duration of the molten tin temperature curve that is within the normal operating temperature range, and the second proportional factor n% of the total duration of the molten tin temperature curve that is outside the normal operating temperature range.

[0027] A set generation subunit is used to generate a first set of molten tin temperatures within the normal operating temperature range from historical detection data, and a second set of molten tin temperatures outside the normal operating temperature range from historical detection data; it removes the molten tin temperatures in the first set located at [t, t] max Elements between [t] and n%; remove elements located in the second tin melt temperature set within [t]. max 2t max The elements between -t] are m%; the number of elements in the first set of molten tin temperatures after removing elements is p, and the number of elements in the second set of molten tin temperatures after removing elements is q.

[0028] The calculation sub-unit is used to calculate the scrap value k according to the following formula:

[0029]

[0030] Where α is the normal influence coefficient, characterizing the impact of each test within the normal operating temperature range on the scrap rate; β is the over-temperature influence coefficient, characterizing the basic impact of each test exceeding the normal operating temperature range on the scrap rate; k is the slope parameter, controlling the sensitivity to temperature influence; t i The solder paste temperature is the temperature at which each test exceeds the normal operating temperature range; t is the preset reference temperature, and the normal temperature range is [t]. min , t max ].

[0031] In a preferred example, this application can be further configured as follows: where α = 0.00006, β = 0.0085, and r = 6.3.

[0032] In a preferred embodiment, the control module may be further configured such that it includes a counting unit for counting the number of detection commands.

[0033] When the number of detection commands reaches a preset number, the scrap value calculation unit calculates the scrap value.

[0034] The second objective of this invention is achieved through the following technical solution:

[0035] A detection method based on any of the aforementioned selective welding equipment liquid level height detection devices includes:

[0036] Receive liquid level detection commands and receive detection values ​​from the laser sensor;

[0037] Drive the tin furnace to a preset coordinate and control the laser sensor for detection;

[0038] Determine whether the detected value falls within a preset range;

[0039] If the detected value does not fall within the preset range, an alarm message will be issued.

[0040] In a preferred embodiment, this application may be further configured to include:

[0041] Based on the historical detection data, the molten solder temperature curve, and the normal operating temperature range of the laser sensor, the scrap value is calculated. The molten solder temperature curve is a function of temperature with respect to time.

[0042] If the scrap value reaches the preset value, a replacement prompt message will be issued.

[0043] In a preferred embodiment, this application can be further configured to: calculate a scrap value based on the historical detection data, the molten solder temperature profile, and the normal operating temperature range of the laser sensor, including:

[0044] Calculate the first proportionality factor m% of the total duration of the molten tin temperature curve within the normal operating temperature range, and the second proportionality factor n% of the total duration of the molten tin temperature curve outside the normal operating temperature range.

[0045] Generate a first set of molten solder temperatures within the normal operating temperature range from historical detection data, and a second set of molten solder temperatures outside the normal operating temperature range from historical detection data; remove molten solder temperatures from the first set located at [t, t] max Elements between [t] and n%; remove elements located in the second tin melt temperature set within [t]. max 2t max The elements between -t] are m%; the number of elements in the first set of molten tin temperatures after removing elements is p, and the number of elements in the second set of molten tin temperatures after removing elements is q.

[0046] The scrap value k is calculated using the following formula:

[0047]

[0048] Where α is the normal influence coefficient, characterizing the impact of each test within the normal operating temperature range on the scrap rate; β is the over-temperature influence coefficient, characterizing the basic impact of each test exceeding the normal operating temperature range on the scrap rate; k is the slope parameter, controlling the sensitivity to temperature influence; t i The solder paste temperature is the temperature at which each test exceeds the normal operating temperature range; t is the preset reference temperature, and the normal temperature range is [t]. min , tmax ].

[0049] In summary, this application includes at least one of the following beneficial technical effects:

[0050] 4. When liquid level needs to be detected, the control unit moves the solder pot to position P1, records the value of the digital laser sensor, and compares it with the standard upper and lower limits. An alarm is triggered when the value exceeds the range, thus improving detection accuracy and equipment compatibility.

[0051] 2. It can predict the lifespan of laser sensors, provide early reminders for replacement, and adjust the elements in the set by removing elements according to the proportion of each temperature range, so that the calculation results are more consistent with the actual temperature conditions and the results are more accurate.

[0052] 3. Even when the temperature is outside the normal operating range, it can still make timely predictions and calculations, and remind you to replace it in advance. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the structure of a welding equipment liquid level height detection device in one embodiment of this application;

[0054] Figure 2 This is a partial structural schematic diagram of a welding equipment liquid level height detection device in one embodiment of this application;

[0055] Figure 3 This is a schematic diagram showing the connection of each module unit of the selective welding equipment liquid level height detection device in one embodiment of this application;

[0056] Figure 4 This is a schematic diagram of the wave soldering temperature profile in one embodiment of this application;

[0057] Figure 5 This is a flowchart illustrating the implementation of the detection method in one embodiment of this application.

[0058] Attached reference numerals: 1. Tin furnace; 2. Laser sensor; 3. Furnace body; 4. Furnace cover; 5. Submerged observation tube. Detailed Implementation

[0059] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of this application, including various details to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0060] It should be noted that the terms "first," "second," etc., used in this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. The implementations described in the following exemplary embodiments do not represent all implementations consistent with this disclosure.

[0061] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.

[0062] The selective welding equipment liquid level height detection device of this application is described below with reference to the accompanying drawings.

[0063] Reference Figure 1 and Figure 2 The soldering equipment liquid level detection device includes a solder pot 1, a drive control component, a laser sensor 2, and a control module. The solder pot 1 is used to hold solder and melt the solid solder in the furnace cavity through a heating device. The solder pot 1 includes a furnace body 3 and a furnace cover 4. The furnace cover 4 is provided with a hollow cylindrical sinking observation tube 5. The sinking observation tube 5 is passed through both ends and extends from the outside of the furnace body 3 to the inside of the furnace body 3. The laser sensor 2 can detect the height of the molten solder in the solder pot 1 through the sinking observation tube 5.

[0064] The drive control component is used to drive the tin pot 1 to rotate in the X, Y, and Z directions. Commonly, the drive control component is a three-axis servo motor module to drive the rotation of the tin pot 1 in the X, Y, and Z directions and record and generate the three-axis coordinates in real time.

[0065] The control module includes a receiving unit, a control unit, a judgment unit, and an alarm unit. The receiving unit is used to receive liquid level detection commands and to receive detection values ​​from the laser sensor 2. The liquid level detection commands are initiated by the operator or detected periodically through a pre-set program.

[0066] The control unit is used to drive the solder pot 1 to a preset coordinate in response to the liquid level detection command. The preset coordinate corresponds to the physical position of the solder pot 1 where the laser sensor 2 can detect the height of the molten solder in the solder pot 1 through the sinking observation tube 5.

[0067] The preset coordinates and preset ranges are determined as follows: A digital laser sensor 2 is installed and fixed. The control unit moves the top surface of the solder pot lid 4 (without holes) directly below the laser sensor 2. At this point, the XYZ coordinate values ​​are recorded (marked as P0), and the value of the laser sensor 2 is also recorded. Based on these values ​​and the typical height range of the molten solder, the operator sets standard upper and lower limits to obtain the preset range. The control unit moves the position of the sinking observation tube 5 of the solder pot 1 directly below the laser sensor 2, keeping the Z-axis coordinate value consistent with the Z-axis coordinate value of P0 (if the Z-axis coordinate values ​​are consistent, the top surface is flush with P0). At this point, the XYZ coordinate values ​​are recorded (marked as P1), which are the preset coordinates.

[0068] Reference Figure 3 The judgment unit is used to determine whether the detected value falls within the preset range, and the alarm unit is used to issue an alarm message if the detected value does not fall within the preset range.

[0069] In one embodiment, the receiving module is further configured to receive a lifetime detection command; the control module further includes: a molten solder temperature monitoring unit and a recording unit, wherein the molten solder temperature monitoring unit is configured to monitor the temperature of the molten solder in the molten solder furnace; the recording unit is configured to record the molten solder temperature to form historical detection data when a liquid level detection command is received; the historical detection data is reset after the laser sensor is replaced, thereby forming historical detection data for the entire life cycle of a single laser sensor, and after replacement, the historical detection data of the previous laser sensor is stored and reset, and the detection data of the new laser sensor is re-recorded.

[0070] Because laser sensors are significantly affected by temperature during operation, their lifespan and detection accuracy are greatly impacted. The normal detection temperature range for laser sensors is -45℃ to 75℃, while solder paste temperature can vary from 5℃ to several hundred degrees Celsius. Solder paste temperatures are often higher than the normal range. Therefore, in solutions using laser sensors to detect solder paste temperature in a solder pot, the historical number of laser sensor readings and the solder paste temperature at each reading are recorded. Some of these temperatures fall within the normal detection range, having a smaller impact on lifespan; others exceed the normal range, significantly affecting lifespan, with the impact increasing with higher temperatures. This data facilitates subsequent analysis of the laser sensor's approximate lifespan, allowing for timely replacement and reducing false detections and failures.

[0071] The control module also includes a scrap value calculation unit, which calculates the scrap value based on historical detection data, the solder melt temperature curve, and the normal operating temperature range of the laser sensor. The solder melt temperature curve is a function of temperature with respect to time. If the scrap value reaches the preset value, the alarm unit will issue a replacement prompt.

[0072] Understandably, because the submerged observation tube is directly facing the laser sensor during testing, the high temperature significantly impacts the sensor's lifespan and increases detection accuracy deviation, necessitating frequent replacements and even leading to false alarms due to delayed replacement. Therefore, it is essential to predict the lifespan of the laser sensor to ensure timely replacement and prevent safety incidents.

[0073] The scrap value calculation unit includes a calculation subunit, a set generation subunit, and a calculation subunit. The calculation subunit is used to calculate the first proportional factor m% of the time in the molten tin temperature curve that is within the normal operating temperature range, and the second proportional factor n% of the time in the molten tin temperature curve that is outside the normal operating temperature range.

[0074] Combination Figure 4 Specifically, since this application applies to wave soldering, the solder temperature profile typically includes a preheating section, a thermal compensation temperature adjustment section, a wave soldering section, an inter-wave temperature adjustment section, and a cooling section. Some intervals fall within the normal operating temperature range of the laser sensor, while others do not. This step allows us to obtain the percentage of time the solder temperature profile falls within and outside the normal operating temperature range.

[0075] The set generation subunit is used to generate a first set of molten tin temperatures within the normal operating temperature range from historical detection data, and a second set of molten tin temperatures outside the normal operating temperature range from historical detection data; it removes the molten tin temperatures in the first set located at [t, t] max Elements between [t] and n%; remove elements located in the second tin melt temperature set within [t]. max 2t max The elements between [-t] and m%; the number of elements in the first molten tin temperature set after removing elements is p, and the number of elements in the second molten tin temperature set after removing elements is q; the normal temperature range of the laser sensor is [t]. min , t max Generally speaking, t max At 75℃, t min Given -45℃, t is a preset reference temperature (e.g., 64℃), m is 26%, and n is 74%, elements in the first set of molten tin temperatures falling between [64℃, 75℃] are removed, and elements in the first set of molten tin temperatures falling between [75℃, 86℃] are removed. Specifically, elements in [64℃, 75℃] are removed from largest to smallest, and elements in [75℃, 86℃] are removed from smallest to largest. If there are elements that cannot be divided evenly, the integer part is used to retain the element.

[0076] Understandably, by calculating the proportions of time spent within and outside the normal operating temperature range in the aforementioned solder temperature curve, the influence of temperature deviations during the process from the drive control component moving the solder pot to the laser sensor detection is eliminated. For example, the process from the drive control component moving the solder pot to the laser sensor detection typically takes several seconds. The solder temperature at the time of receiving the liquid level detection command may be within the normal operating temperature range, but outside the normal operating temperature range at the time of laser sensor detection, or vice versa. This factor causes errors in some data. Therefore, adjusting the elements in the set by the proportion of each temperature range makes the calculation results more consistent with the actual temperature conditions, resulting in more accurate results.

[0077] The calculation sub-unit is used to calculate the scrap value k according to the following formula:

[0078]

[0079] Where α is the normal influence coefficient, characterizing the impact of each test within the normal operating temperature range on the scrap rate; β is the over-temperature influence coefficient, characterizing the basic impact of each test exceeding the normal operating temperature range on the scrap rate; r is the slope parameter, controlling the sensitivity to temperature influence; t i This refers to the solder paste temperature at each test point exceeding the normal operating temperature range. Extremely low temperatures, such as below zero degrees Celsius, are not considered here, as the temperature during solder paste processing generally does not fall below 0 degrees Celsius. The algorithm consists of two parts, one calculating the temperature within the normal detection temperature range and the other calculating the temperature outside the normal detection temperature range.

[0080] The normal influence coefficient α can be obtained by statistically analyzing the number of times the laser sensor of this model was actually used to the point of failure within its normal operating temperature range.

[0081] Based on the formula constructed above, the over-temperature influence coefficient β and slope parameter r are trained using multiple sets of historical detection data samples. Each set of historical detection data samples is generated from the historical detection data of the laser sensor used to detect the liquid level height in the wave soldering equipment from its initial use to its eventual scrapping. Then, a machine learning model is used for fitting or training. The normal influence coefficient α can also be obtained based on the aforementioned samples through fitting or training a machine learning model. In one embodiment, α = 0.0000076, β = 0.0085, and r = 6.3.

[0082] In one embodiment, the control module further includes a counting unit for counting the number of detection commands.

[0083] When the number of detection commands reaches a preset number, the scrap value calculation unit calculates the scrap value. The preset number of times can be set based on 80% of the lowest number of elements in the second molten tin temperature set when the laser sensor scraps, in historical detection data. This is to prevent situations where all detections are performed outside the normal operating temperature range. In such cases, timely prediction calculations can still be performed to remind replacement in advance.

[0084] This application also provides a detection method, based on the above-mentioned welding equipment liquid level height detection device, referring to... Figure 5 ,include:

[0085] S1, receives liquid level detection commands and is used to receive detection values ​​from the laser sensor.

[0086] S2. Drive the solder pot to the preset coordinates. The preset coordinates correspond to the physical position of the solder pot where the laser sensor can detect the height of the molten solder inside the solder pot through the sinking observation tube.

[0087] S3. Determine whether the detected value falls within the preset range.

[0088] S4. If the detected value does not fall within the preset range, an alarm message will be issued.

[0089] In one embodiment, the detection method further includes:

[0090] S5. Calculate the scrap value based on historical test data, solder temperature curve, and the normal operating temperature range of the laser sensor. The solder temperature curve is a function of temperature with respect to time.

[0091] S6. If the scrap value reaches the preset value, a replacement prompt message will be issued.

[0092] In one embodiment, S5 includes:

[0093] S51. Calculate the first proportionality factor m% of the total duration of the molten solder temperature curve within the normal operating temperature range, and the second proportionality factor n% of the total duration of the molten solder temperature curve outside the normal operating temperature range.

[0094] S52. Generate a first set of molten solder temperatures within the normal operating temperature range from the historical detection data, and a second set of molten solder temperatures outside the normal operating temperature range from the historical detection data; remove the molten solder temperatures in the first set that are located in the range [t, t] max Elements between [t] and n%; remove elements located in the second tin melt temperature set within [t]. max 2t max The elements between -t] are m%; the number of elements in the first set of molten tin temperatures after removing elements is p, and the number of elements in the second set of molten tin temperatures after removing elements is q.

[0095] S53. The scrap value k is calculated according to the following formula:

[0096]

[0097] Where α is the normal influence coefficient, characterizing the impact of each test within the normal operating temperature range on the scrap rate; β is the over-temperature influence coefficient, characterizing the basic impact of each test exceeding the normal operating temperature range on the scrap rate; k is the slope parameter, controlling the sensitivity to temperature influence; t i The solder paste temperature is the temperature at which each test exceeds the normal operating temperature range; t is the preset reference temperature, and the normal temperature range is [t]. min , t max ].

[0098] For specific limitations on the detection method, please refer to the limitations on the selection of welding equipment liquid level detection device mentioned above, which will not be repeated here. Each step of the above detection method can be implemented in whole or in part by software, hardware, or a combination thereof.

[0099] Various implementations of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, application-specific integrated circuits (ASICs), computer hardware, firmware, software, and / or combinations thereof. These various implementations may include: implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transferring data and instructions to the storage system, the at least one input device, and the at least one output device.

[0100] These computational programs (also referred to as programs, software, software applications, or code) include machine instructions for a programmable processor and can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. As used herein, the terms “machine-readable medium” and “computer-readable medium” refer to any computer program product, device, and / or apparatus (e.g., disk, optical disk, memory, programmable logic device (PLD)) used to provide machine instructions and / or data to a programmable processor, including machine-readable media that receive machine instructions as machine-readable signals. The term “machine-readable signal” refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0101] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the computer. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0102] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as a data server), or computing systems that include middleware components (e.g., an application server), or computing systems that include frontend components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with embodiments of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., a communication network). Examples of communication networks include local area networks (LANs), wide area networks (WANs), and the Internet.

[0103] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this application can be achieved, and this is not limited herein.

[0104] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A liquid level height detection device for selective welding equipment, characterized in that, include: A tin furnace, comprising a furnace body and a furnace cover, wherein the furnace cover is provided with a sunken observation tube extending from the outside of the furnace body to the inside of the furnace body; Drive control components are used to drive the tin furnace to rotate in the X, Y, and Z axes; A laser sensor, which detects the height of molten tin in the tin furnace via a submerged observation tube; The control module includes: The receiving unit is used to receive liquid level detection commands and to receive detection values ​​from the laser sensor. The control unit is used to drive the solder pot to a preset coordinate in response to a liquid level detection command, and to control the laser sensor to perform detection. The preset coordinate corresponds to the physical position of the solder pot where the laser sensor can detect the height of the molten solder in the solder pot through the sinking observation tube. The judgment unit is used to determine whether the detected value falls within a preset range; An alarm unit is used to issue an alarm message if the detected value does not fall within a preset range; The receiving module is also used to receive lifetime detection commands; The control module also includes: The molten tin temperature monitoring unit is used to monitor the temperature of the molten tin inside the tin furnace; A recording unit is used to record the molten tin temperature to form historical detection data when a liquid level detection command is received; the historical detection data is reset after the laser sensor is replaced. The control module also includes: The scrap value calculation unit is used to calculate the scrap value based on the historical detection data, the solder melt temperature curve and the normal operating temperature range of the laser sensor. The solder melt temperature curve is a function of temperature with respect to time. If the scrap value reaches the preset value, the alarm unit will issue a replacement prompt message; The control module also includes: The scrap value calculation unit includes: The calculation subunit is used to calculate the first proportionality factor m% of the total duration of the molten solder temperature curve within the normal operating temperature range, and the second proportionality factor n% of the total duration of the molten solder temperature curve outside the normal operating temperature range. A set generation subunit is used to generate a first set of molten solder temperatures within the normal operating temperature range from historical detection data, and a second set of molten solder temperatures outside the normal operating temperature range from historical detection data; it removes molten solder temperatures from the first set that are located within […]. , Elements between [ ] and n%; remove elements located in the second tin melt temperature set that are [ , The number of elements between m% and ] is calculated as p, and the number of elements in the first set of molten tin temperatures after removing elements is calculated as q. The calculation sub-unit is used to calculate the scrap value k according to the following formula: ； Where α is the normal influence coefficient, which characterizes the impact of each test within the normal operating temperature range on the scrap rate; β is the over-temperature influence coefficient, which characterizes the basic impact of each test exceeding the normal operating temperature range on the scrap rate; and k is the slope parameter, which controls the sensitivity to temperature influence. The solder paste temperature at which each test exceeds the normal operating temperature range; t is the preset reference temperature, and the normal temperature range is [ , ].

2. The selective welding equipment liquid level height detection device as described in claim 1, characterized in that, in, α=0.00006，β=0.0085，r =6.3。 3. The selective welding equipment liquid level height detection device as described in claim 1, characterized in that, The control module also includes a counting unit for counting the number of detection commands; When the number of detection commands reaches a preset number, the scrap value calculation unit calculates the scrap value.

4. A method for detecting the liquid level height in selective welding equipment, characterized in that, The selective welding equipment liquid level height detection device according to any one of claims 1-3 includes: Receive liquid level detection commands and receive detection values ​​from the laser sensor; Drive the tin furnace to a preset coordinate and control the laser sensor for detection; Determine whether the detected value falls within a preset range; If the detected value does not fall within the preset range, an alarm message will be issued.

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