PCBA reflow soldering temperature control method and system

Abstract

The invention discloses a PCBA reflow soldering temperature control method and system, and the method comprises the steps: recognizing a soldering tin structure on the soldering surface of a circuit board through an image collection unit, and calculating the deviation distance between each pin on the soldering surface of the circuit board and the central position of the soldering tin structure; classifying and conveying the circuit boards based on a comparison result of the deviation distance corresponding to each pin of the circuit board and a pin deviation threshold value; the positions of the pins with the deviation distances larger than the pin deviation threshold value on the circuit board are determined, the point-by-point reflow soldering system is transferred to the positions of the pins one by one, and the soldering tin structures with the deviation distances larger than the pin deviation threshold value are subjected to hot melting through the point-by-point reflow soldering system; the tin soldering structure in the hot melting state is adjusted to move until the central position of the tin soldering structure is close to the position of the pin; according to the invention, reflow soldering is only carried out on the welding spots of which the deviation distances are greater than the pin deviation threshold value, so that the problem of secondary offset of other welding spots caused by reflow soldering of the whole circuit board is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of PCBA, and in particular to a temperature control method and system for PCBA reflow soldering. Background Art

[0002] In the PCBA production process, the soldering of electronic components for pin header pins is mostly done by connecting one or more electronic components to contact pads using solder paste (a mixture of solder and flux), and then melting the solder through controlled heating to achieve permanent bonding. Soldering can be performed using different heating methods such as reflow ovens, infrared heating lamps or heat guns.

[0003] Traditionally, reflow soldering for unqualified pin solder joints is mostly performed on all the pin solder joints of the entire circuit board. At this time, the pin solder joints of the entire circuit board are re-melted and the center positions of the solder joints are readjusted, and the originally qualified pin solder joints are also re-melted, thereby increasing the risk of secondary solder joint offset. Summary of the invention

[0004] The purpose of the present invention is to provide a temperature control method and system for PCBA reflow soldering to solve the technical problem that in the prior art, the reflow soldering work for unqualified pin solder joints is mostly performed on all pin solder joints of the entire circuit board, resulting in an increased risk of secondary solder joint offset.

[0005] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0006] A temperature control method for PCBA reflow soldering, comprising the following steps:

[0007] The solder structure on the soldering surface of the circuit board is identified by using an image acquisition unit, and the deviation distance between each pin on the soldering surface of the circuit board and the center position of its solder structure is calculated. Based on the comparison result of the deviation distance corresponding to each pin of the circuit board and the pin deviation threshold, the circuit board is classified and transported;

[0008] Determine the positions of the pins whose deviation spacing is greater than the pin deviation threshold on the circuit board, transfer the point-by-point reflow soldering system to the positions of the pins one by one, melt the solder structure whose deviation spacing is greater than the pin deviation threshold by the point-by-point reflow soldering system, and adjust the solder structure in the hot-melt state to move until the center position of the solder structure is close to the position of the pin.

[0009] As a preferred solution of the present invention, the implementation method of using the image acquisition unit to identify the solder structure on the soldering surface of the circuit board is:

[0010] Acquire a grayscale image of the soldering surface of the circuit board through the image processing unit, and perform binarization processing on the grayscale image;

[0011] Performing edge detection on the binary image to identify each solder structure of the circuit board, and retaining each solder structure of the soldering surface through pixel screening;

[0012] The solder structure is retained by pixel screening, and the image after pixel screening is restored to a grayscale image. Based on the grayscale image, pixel screening is performed on the surrounding area of ​​each solder structure to obtain the pin position in each solder structure.

[0013] As a preferred solution of the present invention, the method for calculating the deviation distance between each pin on the soldering surface of the circuit board and the center position of the solder structure is as follows:

[0014] Constructing a two-dimensional coordinate system for the restored grayscale image, and identifying the coordinate value (x1, y1) corresponding to the center position of each solder structure and the coordinate value (x2, y2) corresponding to the pin position corresponding to each solder structure based on the two-dimensional coordinate system;

[0015] Calculate the deviation distance between the center position of each solder structure and the pin position corresponding to each solder structure

[0016] As a preferred solution of the present invention, based on the comparison results of the coordinate values ​​(x2, y2) corresponding to the pins of each electronic component on the soldering surface of the circuit board and the coordinate values ​​(x1, y1) corresponding to the center position of each solder structure, the offset quadrant of the center position of the solder structure relative to the position of the pin is determined;

[0017] The two-dimensional coordinate system is constructed with the lower left corner of the restored grayscale image as the origin, so that the pins and solder structure of the entire circuit board soldering surface are in the first quadrant of the two-dimensional coordinate system;

[0018] A virtual two-dimensional coordinate system is constructed based on the location of each pin. When x1<x2 and y1<y2, the offset quadrant of the center position of the solder structure relative to the location of the pin is the third offset quadrant.

[0019] When x1<x2 and y1>y2, the offset quadrant of the center position of the solder structure relative to the position of the pin is the second offset quadrant;

[0020] When x1>x2 and y1>y2, the offset quadrant of the center position of the solder structure relative to the position of the pin is the first offset quadrant;

[0021] When x1>x2 and y1<y2, the offset quadrant of the center position of the solder structure relative to the position of the pin is the fourth offset quadrant.

[0022] As a preferred solution of the present invention, the implementation method of classifying and transporting the circuit boards based on the distribution series of the deviation spacing of the circuit boards is as follows:

[0023] Setting a uniform pin deviation threshold between the pin and the center position of the solder structure;

[0024] Based on the obtained deviation distance between each pin and the center position of the solder structure, the deviation distance corresponding to each pin is compared with the pin deviation threshold;

[0025] When the deviation interval of at least one pin of the circuit board is greater than or equal to the pin deviation threshold, the circuit board is moved along the reflow soldering conveying line;

[0026] When there is no pin deviation interval on the circuit board that is smaller than the pin deviation threshold, the circuit board is moved along the normal conveying line.

[0027] As a preferred solution of the present invention, when the circuit board is moved along the reflow soldering conveyor line, the solder structure of the pin is melted by using a point-by-point reflow soldering system for the pin position where the deviation spacing is greater than or equal to the pin deviation threshold and the offset quadrant of the center position of the solder structure relative to the pin position, and the hot air outlet of the macro hot air gun is adjusted to the offset quadrant of the center position of the solder structure relative to the pin position, and the hot air outlet of the macro hot air gun drives the melted solder structure to move toward the pin position until the center position of the solder structure is close to the pin position.

[0028] As a preferred solution of the present invention, the solder structure of the pin is melted by using a point-by-point reflow soldering system, and the hot air outlet of the macro hot air gun drives the melted solder structure to move toward the pin position until the center position of the solder structure is close to the position of the pin. The implementation method is:

[0029] Based on the location of the pins whose deviation interval is greater than or equal to the pin deviation threshold, the point-by-point reflow soldering system is transferred to the corresponding pin locations;

[0030] Adjust the hot air outlet position of the macro hot air gun based on the offset quadrant of the center position of the solder structure relative to the position of the pin, until the hot air outlet of the macro hot air gun is in the offset quadrant of the center position of the solder structure relative to the position of the pin;

[0031] The thermal melting time is set based on the deviation distance d between the center position of each solder structure and the corresponding pin position, until the center position of the solder structure is close to the position of the pin.

[0032] As a preferred solution of the present invention, after the point-by-point reflow soldering system is transferred to the corresponding pin location, a thermal isolation condition is formed around the pin, and the hot air outlet of the macro hot air gun is adjusted to be in the center position of the solder structure and in the offset quadrant relative to the pin location, wherein the hot melting area of ​​the hot air outlet of the macro hot air gun is 1 / 4 of the solder structure of the pin.

[0033] In addition, in order to solve the above technical problems, the present invention provides a temperature control system of a temperature control method for PCBA reflow soldering, comprising:

[0034] An image acquisition unit, used for photographing the solder structure on the soldering surface of the circuit board;

[0035] An image processing unit calculates the deviation distance between each pin on the soldering surface of the circuit board and the center position of the solder structure thereof, and compares the deviation distance with the pin deviation threshold value, so as to identify the pins on the circuit board whose deviation distance is greater than the pin deviation threshold value and the coordinate position of the pin;

[0036] A transmission unit, which continues to transmit the circuit board whose deviation spacing is greater than the pin deviation threshold along the normal transmission line, and transfers the circuit board whose deviation spacing is less than or equal to the pin deviation threshold to the reflow soldering transmission line for transmission;

[0037] The point-by-point reflow soldering system moves point by point according to the coordinates to the position of the pin whose deviation spacing is greater than the pin deviation threshold, and heat-melts the solder structure based on the offset quadrant of the center position of the solder structure relative to the pin, so that the molten solder paste moves obliquely until the center position of the molten solder paste is close to the pin position.

[0038] As a preferred solution of the present invention, the point-by-point reflow soldering system includes an isolation cover, and a hot air outlet that performs a circular rotational motion along the center position of the isolation cover, the hot air outlet rotates along the inner wall of the isolation cover, and the wind direction of the hot air outlet is toward the pin position;

[0039] Among them, the diameter of the isolation cover is the distance between the two through holes of the circuit board. The center position of the isolation cover is moved to the coordinate position of the pin, and the hot air outlet is moved to the offset quadrant of the center position of the solder structure relative to the pin. The hot air outlet heats and melts the solder structure whose center position deviates from the pin, and drives the melted solder structure to move toward the pin position.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention only performs reflow soldering on solder joints with a deviation spacing greater than the pin deviation threshold, while other qualified pin solder joints do not need to be reflowed, and targeted movement is performed on the offset direction of the solder structure, so that the center position of the solder structure of the hot-melted solder joint gradually approaches the pin, and finally the offset spacing between the center position of the solder structure of the solder joint and the pin is made smaller than the pin deviation threshold, meeting the quality requirements, thereby preventing the problem of secondary offset of other solder joints caused by reflow soldering of the entire circuit board, and the implementation method is simpler and more convenient.

[0042] Among them, when reflowing the solder joints whose deviation spacing is greater than the pin deviation threshold, the offset quadrant of the center position of the solder structure relative to the corresponding pin is determined, and the hot air with the wind direction toward the pin is set in the corresponding offset quadrant to melt the solder structure first and move it toward the pin, thereby reducing the deviation spacing between the center position of the solder structure and the pin until it is less than the pin deviation threshold, thereby realizing the adjustment of the solder structure of a single pin, and the adjustment method is relatively accurate and simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the implementation of the present invention or the technical solution in the prior art, the following briefly introduces the drawings required for the implementation or the prior art description. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0044] Figure 1 A schematic flow chart of a reflow soldering temperature control method according to an embodiment of the present invention;

[0045] Figure 2 It is a structural block diagram of a reflow soldering temperature control system according to an embodiment of the present invention;

[0046] The numbers in the figure represent the following:

[0047] 1-image acquisition unit; 2-image processing unit; 3-transmission unit; 4-point-by-point reflow soldering system. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] like Figure 1 As shown, the present invention provides a temperature control method for PCBA reflow soldering, comprising the following steps:

[0050] The image acquisition unit is used to identify the solder structure on the soldering surface of the circuit board, and the deviation distance between each pin on the soldering surface of the circuit board and the center position of its solder structure is calculated. Based on the comparison result of the deviation distance corresponding to each pin of the circuit board and the pin deviation threshold, the circuit board is classified and transported.

[0051] Determine the positions of the pins whose deviation spacing is greater than the pin deviation threshold on the circuit board, transfer the point-by-point reflow soldering system to the positions of the pins one by one, melt the solder structure whose deviation spacing is greater than the pin deviation threshold by the point-by-point reflow soldering system, and adjust the solder structure in the hot-melt state to move until the center position of the solder structure is close to the position of the pin.

[0052] In this embodiment, the main process of the temperature control method is:

[0053] When the welding surface of the circuit board passes through the image acquisition unit, an image of the welding surface is captured, and through image processing, the deviation spacing between the pin of each electronic component and the center position of its corresponding solder joint is identified, and the deviation spacing of each solder joint on the circuit board is compared with the set pin deviation threshold. When there is at least one solder point deviation spacing greater than the pin deviation threshold on the circuit board, it means that the circuit board is of unqualified quality, and it is necessary to adjust the solder structure of the solder joint on the circuit board whose deviation spacing is greater than the pin deviation threshold, and make the solder structure of the solder joint as close to the pin position as possible, and the solder structure of other solder joints whose deviation spacing is greater than the pin deviation threshold remains unchanged.

[0054] Among them, the specific implementation method of adjusting the solder structure of the solder joint whose deviation spacing is greater than the pin deviation threshold is to use the point-by-point reflow soldering system to hot-melt the solder structure of each solder joint, and use the offset direction of the solder structure relative to the pin to adjust the solder structure in the hot-melt state to move toward the pin until the center position of the solder structure is close to the position of the pin, and finally make the offset spacing between the center position of the solder structure of the solder joint and the pin less than the pin deviation threshold.

[0055] Traditionally, reflow soldering for unqualified pin solder joints is mostly performed on all the pin solder joints of the entire circuit board. At this time, the pin solder joints of the entire circuit board are re-melted and the center positions of the solder joints are readjusted, and the originally qualified pin solder joints are also re-melted, thereby increasing the risk of secondary solder joint offset.

[0056] The present embodiment only performs reflow soldering on solder joints with deviation spacing greater than the pin deviation threshold, while other qualified pin solder joints do not need to be reflowed, and targeted movement is performed on the offset direction of the solder structure, so that the center position of the solder structure of the hot-melted solder joint gradually approaches the pin, and the offset spacing between the pin and the center position of the solder structure of the solder joint is reduced, and ultimately the offset spacing between the center position of the solder structure of the solder joint and the pin is less than the pin deviation threshold, meeting the quality requirements, thereby preventing the problem of secondary offset of other solder joints caused by reflow of the entire circuit board, and the implementation method is simpler and more convenient.

[0057] The implementation method of using the image acquisition unit to identify the solder structure on the soldering surface of the circuit board is as follows:

[0058] Acquire a grayscale image of the soldering surface of the circuit board through the image processing unit, and perform binarization processing on the grayscale image;

[0059] Performing edge detection on the binary image to identify each solder structure of the circuit board, and retaining each solder structure of the soldering surface through pixel screening;

[0060] The solder structure is retained by pixel screening, and the image after pixel screening is restored to a grayscale image. Based on the grayscale image, pixel screening is performed on the surrounding area of ​​each solder structure to obtain the pin position in each solder structure.

[0061] The method for calculating the deviation distance between each pin on the soldering surface of the circuit board and the center position of its solder structure is as follows:

[0062] Constructing a two-dimensional coordinate system for the restored grayscale image, and identifying the coordinate value (x1, y1) corresponding to the center position of each solder structure and the coordinate value (x2, y2) corresponding to the pin position corresponding to each solder structure based on the two-dimensional coordinate system;

[0063] Calculate the deviation distance between the center position of each solder structure and the pin position corresponding to each solder structure

[0064] In this embodiment, by calculating the deviation spacing d between each solder structure on the circuit board and its corresponding pin, and by comparing the deviation spacing d of all solder structures with the pin deviation threshold, the number of unqualified solder joints on each circuit board can be determined, and by constructing a two-dimensional coordinate system, the pin coordinate value (x2, y2) corresponding to the solder joint can be obtained.

[0065] When reflowing an unqualified solder joint whose deviation spacing d is greater than the pin deviation threshold, the offset phase of the center position of the solder structure of the solder joint relative to the pin is specifically determined. For example, when the center position of the solder structure is at the upper right corner of the pin position, hot air with the wind direction toward the pin is applied at the upper right corner to melt the solder structure by heating, and the wind force is used to move the solder structure in a hot-melt state toward the pin position until the deviation spacing between the center position of the solder structure and the pin is less than or equal to the pin deviation threshold.

[0066] Among them, the specific method for determining the offset phase of the center position of the solder structure of the solder joint relative to the pin is: based on the coordinate values ​​(x2, y2) corresponding to the pin of each electronic component on the soldering surface of the circuit board, and the comparison results of the horizontal and vertical coordinates in the coordinate values ​​(x1, y1) corresponding to the center position of each solder structure, determine the offset quadrant of the center position of the solder structure relative to the position of the pin.

[0067] A two-dimensional coordinate system is constructed with the lower left corner of the restored grayscale image as the origin, so that the pins and solder structure of the entire circuit board welding surface are in the first quadrant of the two-dimensional coordinate system.

[0068] A virtual two-dimensional coordinate system is constructed based on the location of each pin. When x1<x2 and y1<y2, the offset quadrant of the center position of the solder structure relative to the location of the pin is the third offset quadrant.

[0069] When x1<x2 and y1>y2, the offset quadrant of the center position of the solder structure relative to the position of the lead is the second offset quadrant.

[0070] When x1>x2 and y1>y2, the offset quadrant of the center position of the solder structure relative to the position of the pin is the first offset quadrant.

[0071] When x1>x2 and y1<y2, the offset quadrant of the center position of the solder structure relative to the position of the pin is the fourth offset quadrant.

[0072] An image processing unit is used to determine circuit boards with a deviation distance between the center position of the solder structure and the pin that is greater than the pin deviation threshold, and based on the above-mentioned implementation method of determining the offset phase of the center position of the solder structure of the solder joint relative to the pin, the offset quadrant of the center position of the solder structure relative to the pin is determined, and the circuit board is defined as a bad board that requires reflow, and the circuit board without a deviation distance between the center position of the solder structure and the pin that is greater than the pin deviation threshold is defined as a good board and transported normally.

[0073] That is, the implementation method of classifying and transporting the circuit boards based on the distribution series of the deviation spacing of the circuit boards is:

[0074] Setting a uniform pin deviation threshold between the pin and the center position of the solder structure;

[0075] Based on the obtained deviation distance between each pin and the center position of the solder structure, the deviation distance corresponding to each pin is compared with the pin deviation threshold;

[0076] When the deviation interval of at least one pin of the circuit board is greater than or equal to the pin deviation threshold, the circuit board is moved along the reflow soldering conveying line;

[0077] When there is no pin deviation interval on the circuit board that is smaller than the pin deviation threshold, the circuit board is moved along the normal conveying line.

[0078] When the circuit board is moved along the reflow soldering conveyor line, the solder structure of the pin is melted by using a point-by-point reflow soldering system for the pin position where the deviation spacing is greater than or equal to the pin deviation threshold and the offset quadrant of the center position of the solder structure relative to the pin position, and the hot air outlet of the macro hot air gun is adjusted to the offset quadrant of the center position of the solder structure relative to the pin position. The hot air outlet of the macro hot air gun drives the melted solder structure to move toward the pin position until the center position of the solder structure is close to the pin position.

[0079] The solder structure of the pin is melted by using a point-by-point reflow soldering system, and the hot air outlet of the macro hot air gun drives the melted solder structure to move toward the pin position until the center position of the solder structure is close to the position of the pin. The implementation method is as follows:

[0080] Based on the location of the pins whose deviation interval is greater than or equal to the pin deviation threshold, the point-by-point reflow soldering system is transferred to the corresponding pin locations;

[0081] Adjust the hot air outlet position of the macro hot air gun based on the offset quadrant of the center position of the solder structure relative to the position of the pin, until the hot air outlet of the macro hot air gun is in the offset quadrant of the center position of the solder structure relative to the position of the pin;

[0082] The thermal melting time is set based on the deviation distance between the center position of each solder structure and the corresponding pin position, until the center position of the solder structure is close to the position of the pin.

[0083] That is, if it is determined through the image processing unit that the center position of a certain solder structure is in the first quadrant position of the corresponding pin, then after the point-by-point reflow soldering system is transferred to the position of the corresponding pin, a thermal isolation condition is formed around the pin, and the hot air outlet of the macro hot air gun is adjusted to be in the first quadrant position of the virtual two-dimensional coordinate system formed by the pin. The hot melting area of ​​the hot air outlet of the macro hot air gun is 1 / 4 of the solder structure of the pin. The hot air outlet of the macro hot air gun first heats and melts the solder structure, and then uses wind force to drive the solder structure to move toward the pin position until the center position of the solder structure gradually approaches the pin and reduces the deviation distance between the pin. At this time, it is considered that the center position of the solder structure is close to the position of the pin, and the solder structure of the pin is a qualified structure.

[0084] If it is determined through the image processing unit that the center position of a certain solder structure is in the second quadrant position of the corresponding pin, the point-by-point reflow soldering system is transferred to the corresponding pin position, a thermal isolation condition is formed around the pin, and the hot air outlet of the macro hot air gun is adjusted to be in the second quadrant position of the virtual two-dimensional coordinate system formed by the pin. The hot melting area of ​​the hot air outlet of the macro hot air gun is 1 / 4 of the solder structure of the pin. The hot air outlet of the macro hot air gun first heats and melts the solder structure, and then uses wind force to drive the solder structure to move toward the pin position until the center position of the solder structure gradually approaches the pin and reduces the deviation distance between the pin. At this time, it is considered that the center position of the solder structure is close to the pin position, and the solder structure of the pin is a qualified structure.

[0085] By analogy, first adjust the entire point-by-point reflow soldering system to transfer to the pin position, and build thermal isolation conditions with the pin as the center, then adjust the hot air outlet of the macro hot air gun relative to the quadrant position of the virtual two-dimensional coordinate system with the pin as the origin, and gradually move the solder structure that deviates from the pin toward the position of the pin, reducing the distance between the center position of the solder structure and the pin, thereby ensuring that the unqualified solder point is adjusted to a solder point with a qualified deviation distance between the center position of the solder structure and its corresponding pin position.

[0086] In addition, this embodiment also provides a temperature control system of the temperature control method of the PCBA reflow soldering. Figure 2 As shown, it specifically includes: an image acquisition unit 1, an image processing unit 2, a transmission unit 3 and a point-by-point reflow welding system 4.

[0087] The image acquisition unit 1 is used to photograph the solder structure on the soldering surface of the circuit board;

[0088] The image processing unit 2 calculates the deviation distance between each pin on the soldering surface of the circuit board and the center position of its solder structure, and compares the deviation distance with the pin deviation threshold to identify the pin on the circuit board with a deviation distance greater than the pin deviation threshold and the coordinate position of the pin;

[0089] The transmission unit 3 continues to transmit the circuit board whose deviation spacing is greater than the pin deviation threshold according to the normal transmission line, and transfers the circuit board whose deviation spacing is less than or equal to the pin deviation threshold to the reflow soldering transmission line for transmission;

[0090] The point-by-point reflow soldering system 4 moves point by point according to the coordinates to the position of the pin whose deviation spacing is greater than the pin deviation threshold, and hot-melts the solder structure based on the offset quadrant of the center position of the solder structure relative to the pin, so that the molten solder paste moves obliquely until the center position of the molten solder paste is close to the pin position.

[0091] The point-by-point reflow soldering system 4 includes an isolation cover, and a hot air outlet that performs a circular rotational motion along the center position of the isolation cover, wherein the hot air outlet rotates along the inner wall of the isolation cover, and the wind direction of the hot air outlet is toward the pin position;

[0092] Among them, the diameter of the isolation cover is the distance between the two through holes of the circuit board. The center position of the isolation cover is moved to the coordinate position of the pin, and the hot air outlet is moved to the offset quadrant of the center position of the solder structure relative to the pin. The hot air outlet heats and melts the solder structure whose center position deviates from the pin, and drives the melted solder structure to move toward the pin position.

[0093] This implementation only performs reflow on solder joints with a deviation spacing greater than the pin deviation threshold, while other qualified pin solder joints do not need to be reflowed, and targeted movement is performed on the offset direction of the solder structure, so that the center position of the solder structure of the hot-melted solder joint gradually approaches the pin, and the offset spacing between the pin and the center position of the solder structure of the solder joint is reduced, and ultimately the offset spacing between the center position of the solder structure of the solder joint and the pin is smaller than the pin deviation threshold, meeting the quality requirements, thereby preventing the problem of secondary offset of other solder joints caused by reflow of the entire circuit board, and the implementation method is simpler and more convenient.

[0094] Among them, when reflowing the solder joints whose deviation spacing is greater than the pin deviation threshold, the offset quadrant of the center position of the solder structure relative to the corresponding pin is determined, and the hot air with the wind direction toward the pin is set in the corresponding offset quadrant to melt the solder structure first and move it toward the pin, thereby reducing the deviation spacing between the center position of the solder structure and the pin until it is less than the pin deviation threshold, thereby realizing the adjustment of the solder structure of a single pin, and the adjustment method is relatively accurate and simple.

[0095] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A temperature control method for PCBA reflow soldering, characterized in that: The following steps are involved: The solder structure on the soldering surface of the circuit board is identified by using an image acquisition unit, and the deviation distance between each pin on the soldering surface of the circuit board and the center position of its solder structure is calculated. Based on the comparison result of the deviation distance corresponding to each pin of the circuit board and the pin deviation threshold, the circuit board is classified and transported; Determine the positions of the pins whose deviation spacing is greater than the pin deviation threshold on the circuit board, transfer the point-by-point reflow soldering system to the positions of the pins one by one, melt the solder structure whose deviation spacing is greater than the pin deviation threshold by the point-by-point reflow soldering system, and adjust the solder structure in the hot-melt state to move until the center position of the solder structure is close to the position of the pin.

2. A temperature control method for PCBA reflow soldering according to claim 1, characterized in that: The implementation method of using the image acquisition unit to identify the solder structure on the soldering surface of the circuit board is as follows: Acquire a grayscale image of the soldering surface of the circuit board through the image processing unit, and perform binarization processing on the grayscale image; Performing edge detection on the binary image to identify each solder structure of the circuit board, and retaining each solder structure of the soldering surface through pixel screening; The solder structure is retained by pixel screening, and the image after pixel screening is restored to a grayscale image. Based on the grayscale image, pixel screening is performed on the surrounding area of ​​each solder structure to obtain the pin position in each solder structure.

3. A temperature control method for PCBA reflow soldering according to claim 2, characterized in that: The method for calculating the deviation distance between each pin on the soldering surface of the circuit board and the center position of its solder structure is as follows: Constructing a two-dimensional coordinate system for the restored grayscale image, and identifying the coordinate value (x1, y1) corresponding to the center position of each solder structure and the coordinate value (x2, y2) corresponding to the pin position corresponding to each solder structure based on the two-dimensional coordinate system; Calculate the deviation distance between the center position of each solder structure and the pin position corresponding to each solder structure 4. A temperature control method for PCBA reflow soldering according to claim 3, characterized in that: Based on the comparison results of the coordinate values ​​(x2, y2) corresponding to the pins of each electronic component on the soldering surface of the circuit board and the coordinate values ​​(x1, y1) corresponding to the center position of each solder structure, the offset quadrant of the center position of the solder structure relative to the position of the pin is determined; The two-dimensional coordinate system is constructed with the lower left corner of the restored grayscale image as the origin, so that the pins and solder structure of the entire circuit board soldering surface are in the first quadrant of the two-dimensional coordinate system; A virtual two-dimensional coordinate system is constructed based on the location of each pin. When x1<x2 and y1<y2, the offset quadrant of the center position of the solder structure relative to the location of the pin is the third offset quadrant. When x1<x2 and y1>y2, the offset quadrant of the center position of the solder structure relative to the position of the pin is the second offset quadrant; When x1>x2 and y1>y2, the offset quadrant of the center position of the solder structure relative to the position of the pin is the first offset quadrant; When x1>x2 and y1<y2, the offset quadrant of the center position of the solder structure relative to the position of the pin is the fourth offset quadrant.

5. A temperature control method for PCBA reflow soldering according to claim 3, characterized in that: The implementation method of classifying and transporting the circuit boards based on the distribution series of the deviation spacing of the circuit boards is as follows: Setting a uniform pin deviation threshold between the pin and the center position of the solder structure; Based on the obtained deviation distance between each pin and the center position of the solder structure, the deviation distance corresponding to each pin is compared with the pin deviation threshold; When the deviation interval of at least one pin of the circuit board is greater than or equal to the pin deviation threshold, the circuit board is moved along the reflow soldering conveying line; When there is no pin deviation interval on the circuit board that is smaller than the pin deviation threshold, the circuit board is moved along the normal conveying line.

6. A temperature control method for PCBA reflow soldering according to claim 5, characterized in that: When the circuit board is moved along the reflow soldering conveyor line, the solder structure of the pin is melted by using a point-by-point reflow soldering system for the pin position where the deviation spacing is greater than or equal to the pin deviation threshold and the offset quadrant of the center position of the solder structure relative to the pin position, and the hot air outlet of the macro hot air gun is adjusted to the offset quadrant of the center position of the solder structure relative to the pin position. The hot air outlet of the macro hot air gun drives the melted solder structure to move toward the pin position until the center position of the solder structure is close to the pin position.

7. A temperature control method for PCBA reflow soldering according to claim 6, characterized in that: The solder structure of the pin is melted by using a point-by-point reflow soldering system, and the hot air outlet of the macro hot air gun drives the melted solder structure to move toward the pin position until the center position of the solder structure is close to the position of the pin. The implementation method is as follows: Based on the location of the pins whose deviation interval is greater than or equal to the pin deviation threshold, the point-by-point reflow soldering system is transferred to the corresponding pin locations; Adjust the hot air outlet position of the macro hot air gun based on the offset quadrant of the center position of the solder structure relative to the position of the pin, until the hot air outlet of the macro hot air gun is in the offset quadrant of the center position of the solder structure relative to the position of the pin; The thermal melting time is set based on the deviation distance d between the center position of each solder structure and the corresponding pin position, until the center position of the solder structure is close to the position of the pin.

8. A temperature control method for PCBA reflow soldering according to claim 7, characterized in that: After transferring the point-by-point reflow soldering system to the corresponding pin location, a thermal isolation condition is formed around the pin, and the hot air outlet of the macro hot air gun is adjusted to be in the center of the solder structure and in the offset quadrant relative to the pin location, wherein the hot melting area of ​​the hot air outlet of the macro hot air gun is 1 / 4 of the solder structure of the pin.

9. A temperature control system based on the temperature control method for PCBA reflow soldering according to any one of claims 1 to 8, characterized in that: include: An image acquisition unit (1) is used to photograph the solder structure on the soldering surface of the circuit board; An image processing unit (2) calculates the deviation distance between each pin on the soldering surface of the circuit board and the center position of the solder structure thereof, and compares the deviation distance with a pin deviation threshold value, so as to identify pins on the circuit board whose deviation distance is greater than the pin deviation threshold value and the coordinate position of the pin; A transmission unit (3) is used to continue to transmit the circuit board whose deviation spacing is greater than the pin deviation threshold along the normal transmission line, and to transfer the circuit board whose deviation spacing is less than or equal to the pin deviation threshold to the reflow soldering transmission line for transmission; The point-by-point reflow soldering system (4) moves point by point according to the coordinate value to the position of the pin whose deviation interval is greater than the pin deviation threshold, and heat-melts the solder structure based on the offset quadrant of the center position of the solder structure relative to the pin, so that the molten solder paste moves obliquely until the center position of the molten solder paste approaches the pin position.

10. A temperature control system for PCBA reflow soldering according to claim 9, characterized in that: The point-by-point reflow soldering system (4) comprises an isolation cover and a hot air outlet that performs a circular rotational motion along the center position of the isolation cover, wherein the hot air outlet performs a rotational motion along the inner wall of the isolation cover, and the wind direction of the hot air outlet is toward the pin position; Among them, the diameter of the isolation cover is the distance between the two through holes of the circuit board. The center position of the isolation cover is moved to the coordinate position of the pin, and the hot air outlet is moved to the offset quadrant of the center position of the solder structure relative to the pin. The hot air outlet heats and melts the solder structure whose center position deviates from the pin, and drives the melted solder structure to move toward the pin position.

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