Fine copper removal method for tin liquor in high-reliability PCB (printed circuit board) lead-free tinning process for automobile intelligent driving

Abstract

The invention provides a fine copper removal method for tin liquor in a high-reliability PCB lead-free tinning process for automobile intelligent driving, which comprises the following steps: S100, lead-free tinning treatment is carried out on batch PCBs through a tin furnace, and the tin furnace has a use stagnation period between the treatment of two adjacent PCBs. And S200, performing non-contact measurement on the copper ion concentration of the tin liquid in the tin furnace through an X-ray fluorescence energy disperse spectroscopy in the use stagnation period of the tin furnace so as to obtain an actual measurement value of the copper ions. S300, judging whether the actual measurement value of the copper ions displayed by the X-ray fluorescence energy disperse spectroscopy is greater than or equal to a preset value of the copper ions, if so, stopping the step S100, performing copper removal treatment on the tin furnace, and repeating the steps S100 and S200 after the copper removal treatment; and if not, repeating the steps S100 and S200.

Description

Technical Field

[0001] The present disclosure relates to the field of PCB board production, and in particular to a method for fine copper removal of tin liquid in a lead-free tinning process of a high-reliability PCB board for intelligent driving of automobiles. Background Art

[0002] With the development of intelligent driving technology, the reliability requirements for PCB boards used in intelligent driving are getting higher and higher. In the traditional PCB production process, there is a lead-free tinning process, which uses a clamping manipulator to immerse the PCB board in a tin furnace for 2 to 3 seconds, and then remove it to cool and solidify the tin liquid on the surface of the PCB board to form a tin layer.

[0003] However, when the PCB board is immersed in the tin furnace, it is inevitable that some copper will be dissolved in the tin liquid in the tin furnace, resulting in an increase in the copper ion concentration of the tin liquid in the tin furnace. When the copper ion concentration in the tin liquid is too high, the tin layer on the surface of the PCB board will be oxidized, reducing the protective effect of the tin layer and also reducing the welding reliability of the PCB board. Therefore, it is necessary to control the copper ion concentration of the tin liquid in the tin furnace. The traditional control method is to manually set the standard of copper removal operation according to the number of processed boards or the processing time. However, the content of copper dissolved in the tin furnace is inconsistent for different PCB boards. When the number of processed PCB boards or the processing time of the batch PCB boards have not reached the standard of copper removal operation, the copper ion concentration in the tin furnace has exceeded the standard, resulting in poor protection effect of the tin layer of the PCB boards to be processed subsequently and reducing the welding reliability of the PCB boards to be processed subsequently, thereby reducing the yield rate of the PCB boards. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for fine copper removal of tin liquid in a lead-free tinning process of a high-reliability PCB board for automotive intelligent driving, which can finely remove copper and improve the yield rate of the PCB board.

[0005] The purpose of this disclosure is achieved through the following technical solutions:

[0006] A fine copper removal method for tin liquid in a lead-free tinning process of a high-reliability PCB board for intelligent driving of automobiles comprises the following steps:

[0007] S100, performing lead-free tinning treatment on a batch of PCB boards by using a tin furnace, wherein there is a stagnation period of use of the tin furnace between the treatment of two adjacent PCB boards;

[0008] S200, during the stagnant period of the tin furnace, non-contactly measuring the copper ion concentration of the tin liquid in the tin furnace by using an X-ray fluorescence spectrometer to obtain an actual measurement value of the copper ions;

[0009] S300, determining whether the actual measurement value of copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of copper ions. If so, stop step S100, perform copper removal treatment on the tin furnace, and repeat steps S100 and S200 after the copper removal treatment; if not, repeat steps S100 and S200.

[0010] In one embodiment, in S100, the specific operation of performing lead-free tinning treatment on a batch of PCB boards by using a tin furnace includes:

[0011] S101, placing the PCB board in the tin furnace for immersion treatment by a clamping manipulator;

[0012] S102, using the clamping manipulator to remove the PCB board after the immersion treatment;

[0013] S103, the clamping robot repeats steps S101 and S102 to perform tinning treatment on the batches of PCB boards.

[0014] In one embodiment, S200 further includes the following steps:

[0015] During the stagnant period of the tin furnace, the nickel ion concentration of the tin liquid in the tin furnace is measured in a non-contact manner by the X-ray fluorescence spectrometer to obtain the actual measured value of the nickel ions.

[0016] In one embodiment, S300 further includes the following steps:

[0017] Determine whether the actual measurement value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions. If so, repeat steps S100 and S200; if not, stop step S100, perform nickel addition treatment on the tin furnace, and repeat steps S100 and S200 after the nickel addition treatment.

[0018] In one embodiment, S200 further includes the following steps:

[0019] During the stagnant period of the tin furnace, the concentration of germanium ions in the tin liquid in the tin furnace is measured in a non-contact manner by the X-ray fluorescence spectrometer to obtain the actual measured value of the germanium ions.

[0020] In one embodiment, S300 further includes the following steps:

[0021] Determine whether the actual measurement value of germanium ions displayed by the X-ray fluorescence spectrometer is within the preset range of germanium ions. If so, repeat steps S100 and S200; if not, stop step S100, add germanium to the tin furnace, and repeat steps S100 and S200 after the germanium addition treatment.

[0022] In one embodiment, the preset value of copper ions is 10000 PPM.

[0023] In one of the embodiments, the preset range of nickel ions is 300 PPM to 700 PPM.

[0024] In one embodiment, the preset range of germanium ions is 50 PPM to 100 PPM.

[0025] In one embodiment, the temperature in the tin furnace is 260°C to 280°C.

[0026] Compared with the prior art, the present invention has at least the following advantages:

[0027] 1. During the stagnation period of the tin furnace, the copper ion concentration of the tin liquid in the tin furnace is measured non-contactly by an X-ray fluorescence spectrometer to obtain the actual measurement value of the copper ions. When the actual measurement value of the copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of the copper ions, there is no need to stop the lead-free tinning of the PCB board. When the actual measurement value of the copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of the copper ions, stop the lead-free tinning of the PCB board, and then remove the copper from the tin furnace to reduce the copper ion concentration of the tin liquid in the tin furnace. This can avoid the situation where the copper content of the tin layer on the PCB board is too high, thereby improving the protection effect of the tin layer of the PCB board and the welding reliability of the PCB board, thereby effectively improving the yield rate of the PCB board.

[0028] 2. During the stagnation period of the tin furnace, the copper ion concentration of the tin liquid in the tin furnace is measured. This can not only obtain the actual measurement value of the copper ion in the tin liquid in the tin furnace after each PCB board is processed, but also does not delay the lead-free tinning treatment of the next PCB board. In this way, the copper ion concentration of the tin liquid in the tin furnace can be monitored in real time, thereby achieving fine copper removal and effectively improving the production efficiency of PCB boards. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 This is a flow chart of a method for fine copper removal of tin liquid in a lead-free tinning process of a high-reliability PCB board for automotive intelligent driving in one embodiment;

[0031] Figure 2 This is a flow chart of step S100 in the fine copper removal method of tin liquid in the lead-free tinning process of high-reliability PCB boards for automotive intelligent driving;

[0032] Figure 3 This is a physical picture of the tin furnace equipment in the fine copper removal method of the tin liquid in the lead-free tinning process of high-reliability PCB boards used in automotive intelligent driving;

[0033] Figure 4 This is a physical picture of the X-ray fluorescence spectrometer used in the fine copper removal method of tin liquid in the lead-free tinning process of high-reliability PCB boards used in automotive intelligent driving. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0035] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0037] The present disclosure provides a method for fine copper removal of tin liquid in the lead-free tinning process of high-reliability PCB boards for intelligent driving of automobiles, comprising the following steps: S100, performing lead-free tinning treatment on batches of PCB boards through a tin furnace, wherein the tin furnace has a stagnation period between the treatment of two adjacent PCB boards. S200, during the stagnation period of the tin furnace, non-contact measurement of the copper ion concentration of the tin liquid in the tin furnace by an X-ray fluorescence spectrometer to obtain the actual measurement value of the copper ions. S300, determining whether the actual measurement value of the copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of the copper ions, if so, stopping step S100, performing copper removal treatment on the tin furnace, and repeating steps S100 and S200 after the copper removal treatment; if not, repeating steps S100 and S200.

[0038] The above-mentioned fine copper removal method, during the stagnation period of the use of the tin furnace, uses an X-ray fluorescence spectrometer to perform non-contact measurement of the copper ion concentration of the tin liquid in the tin furnace to obtain the actual measurement value of the copper ions. When the actual measurement value of the copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of the copper ions, there is no need to stop the lead-free tinning treatment of the PCB board. When the actual measurement value of the copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of the copper ions, the lead-free tinning treatment of the PCB board is stopped, and then the tin furnace is subjected to copper removal treatment to reduce the copper ion concentration of the tin liquid in the tin furnace, so as to avoid the situation where the copper content of the tin layer on the PCB board is too high, thereby improving the protection effect of the tin layer of the PCB board and the welding reliability of the PCB board, thereby effectively improving the yield rate of the PCB board.

[0039] Furthermore, during the stagnant period of the tin furnace, the copper ion concentration of the tin liquid in the tin furnace is measured, which not only can obtain the actual measurement value of the copper ion in the tin liquid in the tin furnace after each PCB board is processed, but also does not delay the lead-free tinning treatment of the next PCB board. In this way, the copper ion concentration of the tin liquid in the tin furnace can be monitored in real time, thereby achieving fine copper removal, and at the same time can effectively improve the production efficiency of PCB boards.

[0040] See also Figure 1 In order to better understand the fine copper removal method of the tin liquid in the lead-free tinning process of the high-reliability PCB board for automobile intelligent driving disclosed in the present invention, the fine copper removal method of the tin liquid in the lead-free tinning process of the high-reliability PCB board for automobile intelligent driving is further explained below:

[0041] A method for fine copper removal of tin liquid in a lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to one embodiment comprises the following steps:

[0042] S100, performing lead-free tinning treatment on batches of PCB boards by using a tin furnace, wherein there is a stagnation period of use of the tin furnace between the treatments of two adjacent PCB boards.

[0043] In this embodiment, since the PCB board needs to go through the process of entering, soaking and exiting the tin furnace, and there is no PCB board in the tin furnace during the period after the PCB board is exited and before the next PCB board is entered, which is the stagnation period of the tin furnace. This can prevent the copper surface of the PCB board from affecting the measurement accuracy of the X-ray fluorescence spectrometer in the next process, thereby improving the measurement accuracy of the copper ion concentration of the tin liquid in the tin furnace.

[0044] Furthermore, in one of the embodiments, the stagnation period of the tin furnace is 5s to 10s.

[0045] Furthermore, in one embodiment, the temperature in the tin furnace is 260° C. to 280° C. It is understandable that the temperature in the tin furnace needs to be controlled between 260° C. and 280° C., so as to ensure that the tin liquid always remains in a fluid state, ensure that the copper surface of the PCB board can be attached with a tin layer, increase the tin layer adhesion surface of the PCB board, thereby improving the protection effect of the tin layer, and effectively improving the welding reliability of the PCB board.

[0046] S200, during the stagnant period of the tin furnace, non-contact measurement of the copper ion concentration of the tin liquid in the tin furnace by means of an X-ray fluorescence spectrometer to obtain an actual measurement value of the copper ions.

[0047] In this embodiment, during the period when the tin furnace is not in use, the copper ion concentration of the tin liquid in the tin furnace is measured non-contactly by using an X-ray fluorescence spectrometer, which will not affect the continuous tinning treatment of the PCB board, thereby improving the production efficiency of the PCB board. At the same time, the actual copper ion content of the tin liquid after each PCB board is tinned in the tin furnace can be obtained, and the copper ion concentration of the tin liquid in the tin furnace can be monitored in real time to avoid the situation where the copper ion concentration of the tin liquid is too high, thereby effectively improving the protection effect of the tin layer on the PCB board and the welding reliability of the PCB board, and then effectively improving the production yield of the PCB board.

[0048] S300, determining whether the actual measurement value of copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of copper ions. If so, stop step S100, perform copper removal treatment on the tin furnace, and repeat steps S100 and S200 after the copper removal treatment; if not, repeat steps S100 and S200.

[0049] In this embodiment, by judging the actual measured value of copper ions displayed on the X-ray fluorescence spectrometer, when the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of copper ions, the lead-free tinning process for the PCB board is immediately stopped, and the copper removal process is performed in the tin furnace, so that the fine copper removal of the tin liquid in the tin furnace can be achieved, the protection effect of the tin layer of the PCB board and the welding reliability of the PCB board are improved, thereby effectively improving the production yield rate of the PCB board. Furthermore, when the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of copper ions, there is no need to stop the lead-free tinning process for the PCB board, thereby improving the production efficiency of the PCB board.

[0050] Furthermore, in one embodiment, the steps of removing copper from the tin furnace are as follows:

[0051] After adding sulfur powder into the tin furnace and stirring thoroughly, the sulfur copper waste slag is removed to reduce the copper ion concentration in the tin liquid.

[0052] It should be noted that the temperature in the tin furnace is between 260°C and 280°C, so that when sulfur powder is added to the tin liquid, it will react to form sulfur copper, and then the sulfur copper waste slag is scooped out through a colander, which can reduce the content of copper ions in the tin liquid.

[0053] See also Figure 2 In one embodiment, in S100, the specific operation of performing lead-free tinning treatment on a batch of PCB boards by using a tin furnace includes:

[0054] S101, placing the PCB board in the tin furnace for immersion treatment by a clamping robot.

[0055] In this embodiment, the PCB board is clamped and transported to the tin furnace by a clamping robot to complete the board loading operation of the PCB board, and is immersed in the tin liquid in the tin furnace so that the surface of the PCB board is adhered to the tin liquid.

[0056] S102, the PCB board after the immersion treatment is taken out by the clamping robot.

[0057] In this embodiment, the PCB board after the immersion treatment in the tin furnace is clamped out by a clamping robot to complete the lead-free tinning treatment of the PCB board.

[0058] Furthermore, the clamping plate robot carries out board processing on the PCB board after the immersion treatment and blows air on the PCB board at the same time. The fan blows air on the surface of the PCB board, which can not only blow the excess tin liquid on the surface of the PCB board back into the tin furnace, but also cool the tin liquid on the PCB board, so that a tin layer is formed on the surface of the PCB board, which can reduce the waste of tin liquid and accelerate the cooling of the tin layer, thereby saving the production cost of the PCB board.

[0059] S103, the clamping robot repeats steps S101 and S102 to perform tinning treatment on the batches of PCB boards.

[0060] In this embodiment, the clamping robot repeats steps S101 and S102 to achieve automated tinning of batches of PCB boards, thereby further improving the production efficiency of PCB boards.

[0061] In one embodiment, S200 further includes the following steps:

[0062] During the stagnant period of the tin furnace, the nickel ion concentration of the tin liquid in the tin furnace is measured in a non-contact manner by the X-ray fluorescence spectrometer to obtain the actual measured value of the nickel ions.

[0063] It should be noted that since the tin liquid in the tin furnace contains trace elements of nickel, the presence of nickel ions can increase the strength and toughness of the solder joints of the tin layer, thereby improving the soldering reliability of the PCB board. At the same time, nickel can also improve the corrosion resistance of the tin layer, which is related to the protective effect of the tin layer. However, when the tin liquid in the tin furnace is subjected to copper removal treatment, nickel ions will be lost along with it, as well as the nickel ions in the tin liquid will be lost during the lead-free tinning process of the PCB board. Therefore, in this embodiment, during the stagnant period of the use of the tin furnace, the nickel ion concentration of the tin liquid in the tin furnace is non-contactly measured by an X-ray fluorescence spectrometer to obtain the actual measured value of the nickel ions, so as to determine whether the nickel ion concentration of the tin liquid in the tin furnace is within the control range, to ensure that each PCB board can be attached with a tin layer with a better protective effect, to improve the soldering reliability of the PCB board, and to further improve the yield rate of the PCB board.

[0064] In one embodiment, S300 further includes the following steps:

[0065] Determine whether the actual measurement value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions. If so, repeat steps S100 and S200; if not, stop step S100, perform nickel addition treatment on the tin furnace, and repeat steps S100 and S200 after the nickel addition treatment.

[0066] It should be noted that when the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions, there is no need to stop the lead-free tinning of the PCB board. When the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is not within the preset range of nickel ions, stop the lead-free tinning of the PCB board, and then add nickel to the tin furnace to increase the nickel ion concentration of the tin liquid in the tin furnace, so as to ensure that each PCB board can be attached with a tin layer with a good protective effect, improve the welding reliability of the PCB board, and further improve the production yield of the PCB board.

[0067] Further, in one embodiment, step S200 is to determine whether the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of copper ions and whether the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions. The specific determination result is:

[0068] When the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of copper ions, steps S100 and S200 are repeated;

[0069] When the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is not within the preset range of nickel ions and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of copper ions, stop step S100, add nickel to the tin furnace, and repeat steps S100 and S200 after the nickel addition;

[0070] When the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is equal to or greater than the preset value of copper ions, stop step S100, perform copper removal treatment on the tin furnace, and repeat steps S100 and S200 after the copper removal treatment;

[0071] When the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is not within the preset range of nickel ions and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is equal to or greater than the preset value of copper ions, stop step S100, perform copper removal treatment on the tin furnace, and then perform nickel addition treatment on the tin furnace after the copper removal treatment, and repeat steps S100 and S200 after the nickel addition treatment, so as to avoid secondary loss of nickel during the copper removal treatment.

[0072] Furthermore, the specific operation steps of adding nickel to the tin furnace are as follows:

[0073] The nickel adding robot clamps the high-nickel tin bars and transports them into the tin furnace to increase the nickel ion concentration in the tin furnace.

[0074] It should be noted that the high-nickel tin bar is added to the tin furnace by a nickel adding robot, and the high-nickel tin bar increases the content in the molten tin after melting to achieve the effect of adding nickel.

[0075] It should be noted that the nickel content of the high-nickel tin bar is 1500PPM. The amount of high-nickel tin bar added is adjusted according to the actual measured value of nickel ions so that the nickel ion concentration of the tin liquid in the tin furnace is within the preset range of nickel ions.

[0076] In one embodiment, S200 further includes the following steps:

[0077] During the stagnant period of the tin furnace, the concentration of germanium ions in the tin liquid in the tin furnace is measured in a non-contact manner by the X-ray fluorescence spectrometer to obtain the actual measured value of the germanium ions.

[0078] It should be noted that, since the tin liquid in the tin furnace contains trace elements of germanium, the presence of germanium ions can inhibit the formation of oxides, improve the stability of the tin layer, and thus improve the welding reliability of the tin layer. At the same time, germanium can increase the wettability and fluidity of the tin liquid, so that the tin liquid can quickly adhere to the surface of the PCB board, and improve the uniformity of the adhesion of the tin liquid on the surface of the PCB board. However, when the tin liquid in the tin furnace is subjected to copper removal treatment, it will be accompanied by the loss of germanium ions and the loss of germanium ions in the tin liquid during the lead-free tinning process of the PCB board. Therefore, in this embodiment, during the stagnant period of the use of the tin furnace, the germanium ion concentration of the tin liquid in the tin furnace is measured non-contactly by an X-ray fluorescence spectrometer to obtain the actual measurement value of the germanium ion, so as to determine whether the germanium ion concentration of the tin liquid in the tin furnace is within the control range, to ensure that each PCB board can be evenly attached to a tin layer with a good protective effect, to improve the welding reliability of the PCB board, and to further improve the yield rate of the PCB board.

[0079] In one embodiment, S300 further includes the following steps:

[0080] Determine whether the actual measurement value of germanium ions displayed by the X-ray fluorescence spectrometer is within the preset range of germanium ions. If so, repeat steps S100 and S200; if not, stop step S100, add germanium to the tin furnace, and repeat steps S100 and S200 after the germanium addition treatment.

[0081] It should be noted that when the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is within the preset range of germanium ions, there is no need to stop the lead-free tinning of the PCB board. When the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is not within the preset range of germanium ions, the lead-free tinning of the PCB board is stopped, and then the tin furnace is treated with germanium to increase the germanium ion concentration of the tin liquid in the tin furnace, so as to ensure that each PCB board can be evenly attached with a tin layer with good protective effect, improve the welding reliability of the PCB board, and further improve the production yield of the PCB board.

[0082] Further, the step of S200 is to determine whether the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of copper ions, whether the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions, and whether the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is within the preset range of germanium ions. The specific determination results are:

[0083] When the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is within the preset range of germanium ions, the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions, and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of copper ions, steps S100 and S200 are repeated;

[0084] When the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is not within the preset range of germanium ions, the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions, and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of copper ions, stop step S100, add germanium to the tin furnace, and repeat steps S100 and S200 after adding germanium;

[0085] When the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is within the preset range of germanium ions, the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is not within the preset range of nickel ions, and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of copper ions, stop step S100, add nickel to the tin furnace, and repeat steps S100 and S200 after the nickel addition treatment;

[0086] When the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is not within the preset range of germanium ions, the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is not within the preset range of nickel ions, and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of copper ions, stop step S100, perform germanium addition treatment and nickel addition treatment on the tin furnace respectively, and repeat steps S100 and S200 after both the nickel addition treatment and the germanium addition treatment are completed;

[0087] When the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is within the preset range of germanium ions, the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions, and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is equal to or greater than the preset value of copper ions, stop step S100, perform copper removal treatment on the tin furnace, and repeat steps S100 and S200 after the copper removal treatment;

[0088] When the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is not within the preset range of germanium ions, the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions, and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is equal to or greater than the preset value of copper ions, stop step S100, perform copper removal treatment on the tin furnace, then perform germanium addition treatment on the tin furnace after the copper removal treatment, and repeat steps S100 and S200 after the germanium addition treatment, so as to avoid secondary loss of germanium caused by the copper removal treatment;

[0089] When the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is within the preset range of germanium ions, the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is not within the preset range of nickel ions, and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is equal to or greater than the preset value of copper ions, stop step S100, perform copper removal treatment on the tin furnace, and then perform nickel addition treatment on the tin furnace after the copper removal treatment, and repeat steps S100 and S200 after the nickel addition treatment, so as to avoid secondary loss of nickel during the copper removal treatment.

[0090] When the actual measured value of germanium ions displayed by the X-ray fluorescence spectrometer is not within the preset range of germanium ions, the actual measured value of nickel ions displayed by the X-ray fluorescence spectrometer is not within the preset range of nickel ions, and the actual measured value of copper ions displayed by the X-ray fluorescence spectrometer is equal to or greater than the preset value of copper ions, stop step S100, perform copper removal treatment on the tin furnace, and then perform germanium addition treatment and nickel addition treatment on the tin furnace after the copper removal treatment, and repeat steps S100 and S200 after the germanium addition treatment and the nickel addition treatment are completed, so as to avoid secondary loss of germanium and nickel during the copper removal treatment.

[0091] It can be understood that since the X-ray fluorescence spectrometer uses non-contact measurement, that is, remotely measures and analyzes the elemental composition in the tin furnace through the element measurement probe, the tin furnace is provided with a stirring mechanism to continuously disturb the tin liquid. Although the tin liquid can be stirred evenly, the dispersion speed of the metal elements at various positions is slow because the tin liquid is in a fluid state. In order to further improve the measurement accuracy of the X-ray fluorescence spectrometer. In one embodiment, during the stagnant period of the use of the tin furnace, the copper ion concentration at multiple sites of the tin liquid in the tin furnace is measured non-contactly by the X-ray fluorescence spectrometer to obtain multiple actual measurement values ​​of copper ions. By averaging the actual measurement values ​​of multiple copper ions to obtain the average actual measurement value of copper ions, the measurement accuracy of copper ions by the X-ray fluorescence spectrometer can be further improved. Furthermore, in one of the embodiments, during the stagnant period of use of the tin furnace, the copper ion concentration of a single site of the tin liquid in the tin furnace is measured multiple times by non-contact measurement using the X-ray fluorescence spectrometer to obtain actual measurement values ​​of multiple copper ions at a single site, and then the actual measurement values ​​of multiple copper ions at a single site are averaged to obtain the average actual measurement value of copper ions at a single site, thereby improving the accuracy of the copper ion concentration measurement at a single site, and then the average actual measurement values ​​of copper ions at multiple sites are averaged to improve the accuracy of the actual measurement values ​​of copper ions, thereby achieving fine copper removal of the tin liquid and further improving the production yield of PCB boards.

[0092] Furthermore, in one of the embodiments, during the stagnant period of use of the tin furnace, the nickel ion concentration at multiple sites of the tin liquid in the tin furnace is non-contactly measured by the X-ray fluorescence spectrometer to obtain multiple actual measurement values ​​of nickel ions, and the actual measurement values ​​of multiple nickel ions are averaged to obtain an average actual measurement value of nickel ions, thereby further improving the measurement accuracy of nickel ions by the X-ray fluorescence spectrometer. Furthermore, in one of the embodiments, during the stagnant period of use of the tin furnace, the X-ray fluorescence spectrometer is used to perform multiple non-contact measurements of the nickel ion concentration at a single site of the tin liquid in the tin furnace to obtain actual measurement values ​​of multiple nickel ions at a single site, and then the actual measurement values ​​of multiple nickel ions at a single site are averaged to obtain the average actual measurement value of nickel ions at a single site, thereby improving the accuracy of the nickel ion concentration measurement at a single site, and then averaging the average actual measurement values ​​of nickel ions at multiple sites to improve the accuracy of the actual measurement values ​​of nickel ions, ensuring that the nickel ions in the tin liquid are within the control range, thereby ensuring that each P PCB boards can be attached with a tin layer with good protective effect, further improving the production yield of PCB boards.

[0093] Furthermore, in one of the embodiments, during the stagnant period of use of the tin furnace, the X-ray fluorescence spectrometer is used to perform non-contact measurement of the germanium ion concentration at multiple locations of the tin liquid in the tin furnace to obtain multiple actual measurement values ​​of the germanium ions, and the actual measurement values ​​of the multiple germanium ions are averaged to obtain an average actual measurement value of the germanium ions, thereby further improving the measurement accuracy of the X-ray fluorescence spectrometer for germanium ions. Furthermore, in one of the embodiments, during the stagnant period of use of the tin furnace, the X-ray fluorescence spectrometer is used to perform multiple non-contact measurements of the germanium ion concentration at a single site of the tin liquid in the tin furnace to obtain actual measurement values ​​of multiple germanium ions at a single site, and then the actual measurement values ​​of multiple germanium ions at a single site are averaged to obtain the average actual measurement value of the germanium ions at a single site, thereby improving the accuracy of the measurement of the germanium ion concentration at a single site, and then averaging the average actual measurement values ​​of the germanium ions at multiple sites to improve the accuracy of the actual measurement values ​​of the germanium ions, ensuring that the germanium ions in the tin liquid are within the control range, thereby ensuring that each P PCB boards can be evenly attached with a tin layer with good protective effect, further improving the production yield of the PCB boards.

[0094] In one embodiment, the copper ion preset value is 10000 PPM. It is understandable that when the copper ion concentration of the tin liquid in the tin furnace is equal to or greater than 10000 PPM, it means that the copper ion concentration is too high, which reduces the protective effect of the tin layer, thereby reducing the welding reliability of the PCB board. By setting the copper ion preset value to 10000 PPM, the copper ion concentration of the tin liquid in the tin furnace can be better controlled, thereby effectively improving the production yield of the PCB board.

[0095] In one embodiment, the preset range of nickel ions is 300PPM to 700PPM. It is understandable that the nickel ion concentration in the tin solution is in the range of 300PPM to 700PPM, which can improve the protection effect of the tin layer. By setting the preset range of nickel ions to 300PPM to 700PPM, the nickel ion concentration of the tin solution in the tin furnace can be better controlled, thereby improving the production yield of PCB boards.

[0096] In one embodiment, the preset range of germanium ions is 50PPM to 100PPM. It is understandable that the germanium ion concentration in the tin solution is in the range of 50PPM to 100PPM, which can improve the protection effect of the tin layer. By setting the preset range of germanium ions to 300PPM to 700PPM, the germanium ion concentration of the tin solution in the tin furnace can be better controlled, thereby improving the production yield of PCB boards.

[0097] Compared with the prior art, the present invention has at least the following advantages:

[0098] 1. During the stagnation period of the tin furnace, the copper ion concentration of the tin liquid in the tin furnace is measured non-contactly by an X-ray fluorescence spectrometer to obtain the actual measurement value of the copper ions. When the actual measurement value of the copper ions displayed by the X-ray fluorescence spectrometer is less than the preset value of the copper ions, there is no need to stop the lead-free tinning of the PCB board. When the actual measurement value of the copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of the copper ions, stop the lead-free tinning of the PCB board, and then remove the copper from the tin furnace to reduce the copper ion concentration of the tin liquid in the tin furnace. This can avoid the situation where the copper content of the tin layer on the PCB board is too high, thereby improving the protection effect of the tin layer of the PCB board and the welding reliability of the PCB board, thereby effectively improving the yield rate of the PCB board.

[0099] 2. During the stagnation period of the tin furnace, the copper ion concentration of the tin liquid in the tin furnace is measured. This can not only obtain the actual measurement value of the copper ion in the tin liquid in the tin furnace after each PCB board is processed, but also does not delay the lead-free tinning treatment of the next PCB board. In this way, the copper ion concentration of the tin liquid in the tin furnace can be monitored in real time, thereby achieving fine copper removal and effectively improving the production efficiency of PCB boards.

[0100] The above-described embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. A fine copper removal method for tin liquid in the lead-free tinning process of high-reliability PCB boards for intelligent driving of automobiles, characterized in that: The steps include: S100, performing lead-free tinning treatment on a batch of PCB boards by using a tin furnace, wherein there is a stagnation period of use of the tin furnace between the treatment of two adjacent PCB boards; S200, during the stagnant period of the tin furnace, non-contactly measuring the copper ion concentration of the tin liquid in the tin furnace by using an X-ray fluorescence spectrometer to obtain an actual measurement value of the copper ions; S300, determining whether the actual measurement value of copper ions displayed by the X-ray fluorescence spectrometer is greater than or equal to the preset value of copper ions. If so, stop step S100, perform copper removal treatment on the tin furnace, and repeat steps S100 and S200 after the copper removal treatment; if not, repeat steps S100 and S200.

2. The fine copper removal method of tin liquid in the lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to claim 1 is characterized in that, In S100, the specific operations of lead-free tinning of batches of PCB boards through the tin furnace include: S101, placing the PCB board in the tin furnace for immersion treatment by a clamping manipulator; S102, using the clamping manipulator to remove the PCB board after the immersion treatment; S103, the clamping robot repeats steps S101 and S102 to perform tinning treatment on the batches of PCB boards.

3. The fine copper removal method of tin liquid in the lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to claim 1 is characterized in that, S200 also includes the following steps: During the stagnant period of the tin furnace, the nickel ion concentration of the tin liquid in the tin furnace is measured in a non-contact manner by the X-ray fluorescence spectrometer to obtain the actual measured value of the nickel ions.

4. The fine copper removal method of tin liquid in the lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to claim 3 is characterized in that, S300 also includes the following steps: Determine whether the actual measurement value of nickel ions displayed by the X-ray fluorescence spectrometer is within the preset range of nickel ions. If so, repeat steps S100 and S200; if not, stop step S100, perform nickel addition treatment on the tin furnace, and repeat steps S100 and S200 after the nickel addition treatment.

5. The fine copper removal method of tin liquid in the lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to claim 1 is characterized in that, S200 also includes the following steps: During the stagnant period of the tin furnace, the concentration of germanium ions in the tin liquid in the tin furnace is measured in a non-contact manner by the X-ray fluorescence spectrometer to obtain the actual measured value of the germanium ions.

6. The fine copper removal method of tin liquid in the lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to claim 5 is characterized in that, S300 also includes the following steps: Determine whether the actual measurement value of germanium ions displayed by the X-ray fluorescence spectrometer is within the preset range of germanium ions. If so, repeat steps S100 and S200; if not, stop step S100, add germanium to the tin furnace, and repeat steps S100 and S200 after the germanium addition treatment.

7. The fine copper removal method of tin liquid in the lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to claim 1 is characterized in that, The preset value of copper ions is 10000 PPM.

8. The fine copper removal method of tin liquid in the lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to claim 4 is characterized in that, The preset range of nickel ion value is 300PPM to 700PPM.

9. The fine copper removal method of tin liquid in the lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to claim 6 is characterized in that, The preset range value of the germanium ion is 50PPM to 100PPM.

10. The fine copper removal method of tin liquid in the lead-free tinning process of a high-reliability PCB board for automobile intelligent driving according to claim 1 is characterized in that: The temperature in the tin furnace is 260°C to 280°C.

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