Method for controlling welding of welding hole plug-in by using prefabricated welding flux

Abstract

The invention relates to the technical field of electronic packaging, and discloses a method for controlling welding of a welding hole plug-in by using a prefabricated welding flux, and the method comprises the following steps: S1, dehumidifying and drying: drying a substrate by using a drying oven; s2, a solder column is manufactured, specifically, based on an original welding hole site in the substrate to be welded, the soldering tin amount Vt between the welding hole site and the plug-in is calculated, the size of the solder column is calculated according to the value of the soldering tin amount Vt, and the solder column is manufactured; s3, welding preparation is conducted, specifically, the plug-in, the substrate and the welding flux column are sequentially installed on the clamp body; and S4, reflow soldering. The soldering tin amount is calculated according to the size of a welding hole site needing to be welded and the size of a plug-in, a solid solder column of a fixed mass is manufactured in advance through the calculated soldering tin amount, the soldering tin amount is accurately controlled so as to accurately fill a weld joint, the situation that tin is too much or too little after welding is avoided, the welding quality is improved, and meanwhile the welding quality is improved. During welding, the amount of solder paste does not need to be controlled, and the efficiency can be greatly improved by directly using the solder column and placing the solder column on the plug-in.

Description

Technical Field

[0001] The invention relates to the technical field of electronic packaging, and in particular to a method for controlling welding of a welding hole plug-in by using prefabricated solder. Background Art

[0002] The welding technology of the welding hole plug-in is a circuit packaging technology that inserts the pins of the components into the corresponding welding holes of the printed circuit board, and then welds and fixes them with the circuit pads of the printed circuit board. The welding of the welding hole plug-in is convenient in terms of maintenance and rework, especially manual operation. The welding points of the through-hole plug-in have better mechanical stress and vibration resistance than the surface mount solder points. Therefore, the through-hole plug-in welding technology is widely used in some fields with high requirements for the reliability of circuit products. At present, the welding technology of the welding hole plug-in in the industry is mainly used for the welding scene where the plug-in passes through the welding hole, including wave soldering and manual soldering iron welding technology, while the welding of the plug-in part inserted into the welding hole is rarely involved. At present, this type of plug-in welding generally adopts manual spot coating of solder paste into the welding hole, and the welding of the plug-in and the welding hole is realized by heating and reflow. The manual operation has the problem of uncontrollable amount of solder paste, which is easy to cause the welding points of the welding hole to have more tin or less tin defects after reflow, affecting the production efficiency and production quality. Therefore, for the welding of the plug-in part inserted into the welding hole, a method for controlling the amount of solder in the through-hole plug-in is needed to improve the production efficiency and production quality. Summary of the invention

[0003] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is: to provide a method for controlling the welding of a welding hole plug-in by using prefabricated solder to solve the problem that the amount of solder paste at the welding point of the existing welding hole plug-in is uncontrollable.

[0004] In order to solve the above technical problems, a technical solution adopted by the present invention is: providing a method for controlling welding of a welding hole plug-in using prefabricated solder, comprising the following steps:

[0005] S1. Dehumidification and drying: use an oven to dry the substrate;

[0006] S2. Solder column production: Based on the original soldering holes on the substrate to be soldered, calculate the solder volume V between the soldering holes and the plug-in t , according to the solder volume V t Calculate the solder column size and make the solder column;

[0007] S3, welding preparation: install the plug-in, substrate and solder column on the clamp body in sequence;

[0008] S4, reflow soldering: Place the fixture assembled in step S3 in a reflow oven and start the operation until the solder column melts and fills the weld and then cools and solidifies.

[0009] Through the above method, the amount of solder is calculated according to the welding size and plug-in size to be welded, and then the solder paste with the calculated amount of solder is used to make a solid solder column with fixed solder paste, so as to more accurately control the amount of solder during reflow soldering to accurately fill the weld, thereby improving the welding quality and improving the welding efficiency.

[0010] Furthermore, in the step S2, the portion of the plug-in extending into the soldering hole is called a pin, and the solder amount V t Obtained by the following formula:

[0011] V t =(V2-V1+V)×2(Formula 1)

[0012] In formula (1), V2 is the volume of the inner cavity of the welding hole, V1 is the volume occupied by the pin of the plug-in extending into the welding hole, and V is the volume of the weld after the upper and lower solder pastes are connected; where V2 = π(D / 2) 2 H, V1 = π(d / 2) 2 L, D are the inner diameters of the welding holes, H is the thickness of the welding holes, d is the pin diameter, and L is the length of the pin part of the plug-in that extends into the welding hole. This is so that the amount of solder required for the weld between the pin and the copper ring of the pad can be accurately calculated, so that the solder column can be prepared in advance and used directly when welding is needed and reflow soldered to ensure the welding quality.

[0013] Furthermore, according to the solder volume V t The step of calculating the size of the solder column and making the solder column includes: t The solder column structure is cylindrical, so that the diameter of the solder column is smaller than the solder hole and the difference between the solder column diameter and the solder hole diameter is between 0.2 and 0.4 mm. Determine the solder column diameter; according to the solder volume V t The height h of the solder column is calculated, and the height h of the solder column is obtained by the following formula:

[0014] h=V t / π(d1 / 2) 2 (Formula 2)

[0015] In (Formula 2), d1 is the bottom diameter of the solder column, so as to make an appropriate amount of solder columns, thereby avoiding the situation of too much tin or too little tin during soldering.

[0016] Furthermore, according to the solder volume V t The step of calculating the size of the solder column based on the value of and making the solder column also includes: after confirming the size of the solder column, using solder paste to make the solder column, selecting Sn at low temperature 62 Pb 36 Ag2 is used to make solder pillars, and Sn is used at high temperatures 96.5 Ag3Cu 0.5Make solder pillars to facilitate the formation of solder pillars.

[0017] Furthermore, according to the solder volume V t The step of calculating the size of the solder column according to the value of and making the solder column also includes: the melting point of the solder column is the same as the melting point of the solder paste required by the substrate, so as to ensure that the solder column can be equivalent to the substrate reflow during the reflow process.

[0018] Furthermore, in the S3 step: it includes a clamp body, and a placement groove and a limit groove are coaxially opened in sequence from large to small along the thickness direction on one side surface of the clamp body, so that the placement groove and the limit groove are stepped, and the substrate with welding holes is used to be installed in the placement groove, and a mounting hole for the plug-in to pass through is opened in the limit groove at a position corresponding to the welding hole along the thickness direction, so as to fix the plug-in and the substrate during welding, thereby ensuring the welding between the solder column and the plug-in and the substrate.

[0019] Furthermore, in the S3 step: the plug-in includes the pin, the middle section and the extension section in sequence along its axial direction, the diameter of the pin is smaller than the inner diameter of the welding hole, the diameter of the middle section is larger than the inner diameter of the welding hole and the diameter of the mounting hole, respectively, and the diameter of the extension section is smaller than the diameter of the mounting hole; during assembly, the extension section is passed through the mounting hole from top to bottom, the middle section is located in the limiting groove, the pin extends into the welding hole, and the bottom end of the solder column and the pin are both located in the welding hole to ensure welding strength.

[0020] Furthermore, in the S3 step: the height of the middle section is equal to the depth of the limiting groove, so that after assembly the middle section rests against the bottom wall of the limiting groove and the base plate respectively, so that the base plate and the clamp body cooperate with each other to fix the plug-in, thereby limiting the deflection and shaking of the plug-in.

[0021] Furthermore, in the S3 step: before assembly, the surface of the solder column needs to be coated with flux: the solder column is immersed in the flux solution for 0 to 5 minutes and then taken out, and the weight accuracy of the flux is controlled to be 0.001g; during assembly, the bottom of the solder column is placed on the top of the pin, which helps to remove the oxide on the welding surface and ensure the quality of the welding solder joint.

[0022] Furthermore, in the step S1, the drying temperature is 120±5° C. and the drying time is 1 to 4 hours, so as to remove as much moisture as possible from the substrate to achieve the purpose of dehumidification.

[0023] The method of controlling the welding of a solder hole plug-in by using prefabricated solder of the present invention has at least the following beneficial effects: the amount of solder is calculated according to the size of the welding hole position and the plug-in to be welded, and then the solder paste with the calculated amount of solder is used to pre-make a solid solder column of a fixed volume, so as to more accurately control the amount of solder during reflow soldering to accurately fill the weld, avoid the occurrence of too much tin or too little tin after welding, and improve the welding quality. At the same time, there is no need to control the amount of solder paste during welding, and the efficiency can be greatly improved by directly using the solder column and placing it on the plug-in. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0025] Figure 1 A flowchart of a method for controlling welding of a welding hole plug-in by using prefabricated solder according to the present invention;

[0026] Figure 2 It is a schematic diagram of the structure of the base plate and the plug-in unit of the present invention;

[0027] Figure 3 It is a schematic diagram of the matching structure of the plug-in and the solder column of the present invention;

[0028] Figure 4 It is a structural schematic diagram of the clamp body of the present invention;

[0029] Figure 5 It is a partial cross-sectional view of the substrate and the plug-in after welding of the present invention.

[0030] The meanings of the symbols in the accompanying drawings are:

[0031] Base plate-1; welding hole-11; pad copper ring-12; plug-in-2; pin-21; middle section-22; extension section-23; clamp body-3; placement groove-31; limiting groove-32; mounting hole-33; avoidance groove-34; solder column-4. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] like Figure 2 and Figure 3As shown, the present invention is suitable for welding of a substrate 1 and a plug-in 2. The substrate 1 (printed circuit board) is in a plate-like or sheet-like structure. Two columns or rows of welding holes are provided on the substrate 1. The sizes of the welding holes can be the same or different. The size of the plug-in 2 is adapted to the welding holes. A soldering pad copper ring 12 is installed in each welding hole and is arranged to fit the inner wall of the welding hole. The inner cavity of the soldering pad copper ring 12 is defined as a welding hole 11. The soldering pad copper ring 12 is a common structure in the welding hole of the existing circuit board and will not be described in detail here. The plug-in 2 includes a pin 21, a middle section 22 and an extension section 23 in sequence along its axial direction. The pin 21 can be in a cylindrical structure or a polygonal prism structure, preferably a polygonal prism, and the diameter or bottom edge length of the pin 21 is smaller than the inner diameter of the welding hole 11 so that the pin 21 can pass through the welding hole 11, but the difference between the diameter or bottom edge length of the pin 21 and the inner diameter of the welding hole 11 should be controlled within a small range such as 0 to 2 mm. When the pin 21 is a polygonal column, even if the bottom edge length of the pin 21 is the same as the diameter of the welding hole 11, a space is enclosed between the side surface where each edge is located and the inner wall of the welding hole 11 so that the solder can enter and ensure the contact between the solder and the pin 21 and the inner wall of the welding hole 11, thereby achieving welding. The diameter of the middle section 22 is larger than the inner diameter of the welding hole 11, the pin 21, the middle section 22 and the extension section 23 are coaxial and integrally formed, and the diameter of the extension section 23 is smaller than the diameter of the middle section 22, so that the connection between the middle section 22 and the pin 21 and the connection between the middle section 22 and the extension section 23 form an annular step surface. When the pin 21 penetrates into the welding hole 11, the step surface of the middle section 22 close to the pin 21 can be against the substrate 1, and the length of the pin 21 is smaller than the depth of the welding hole 11. It should be noted that the diameter of the solder column 4 cannot exceed the diameter of the solder hole 11 , otherwise it cannot be used, and the principle should be to facilitate taking and placing in the solder hole 11 .

[0034] like Figures 1 to 5 As shown, the method of controlling the welding of the welding hole plug-in by using prefabricated solder of the present invention comprises the following steps:

[0035] S1, dehumidification and drying: using an oven to dry the substrate 1;

[0036] S2, solder column 4 production: based on the original soldering hole position on the substrate to be soldered, calculate the solder volume Vt between the soldering hole position and the plug-in, and calculate the solder volume Vt according to the solder volume Vt. t Calculate the solder column size and make the solder column;

[0037] S3, welding preparation: install the plug-in 2, the substrate 1 and the solder column 4 on the clamp body 3 in sequence;

[0038] S4, reflow soldering: place the fixture assembled in step S3 in a reflow furnace and start the operation until the solder column 4 melts and fills the solder joint and then cools and solidifies.

[0039] In the step S1: the substrate 1 (printed circuit board) is dried using a drying device, the drying temperature is 120±5°C, and the drying time is 1 to 4 hours. By drying the water vapor on the surface of the substrate 1 and in the welding holes 11 of the substrate 1, the dehumidification and drying pretreatment of the substrate 1 is achieved, thereby eliminating the possibility of void defects at the raw material end of the substrate 1 during the reflow soldering process.

[0040] According to step S2: the size data of the welding hole 11 and the plug-in 2 can be queried through the material information. If the size data is not found in the material information, the size information of the welding hole 11 and the plug-in 2 can be obtained through the corresponding three-dimensional measurement drawings or actual measurement using a vernier caliper. The welding hole 11 is a pre-fixed structure on the welding hole 11 of each substrate 1. For this reason, during the measurement, the inner diameter of each welding hole 11 on the substrate 1 to be welded, that is, the inner diameter of the welding hole 11 in each welding hole 11, is determined by the aforementioned measurement method such as using a vernier caliper in the actual measurement; the outer dimensions of the pin 21 of the plug-in 2 must also be determined, and the maximum length (diameter or bottom edge length) of the pin 21 must be measured along the axial direction of the pin 21 to complete the determination of the size of the welding hole 11 and the size of the plug-in 2. In this way, errors can be avoided in the subsequent welding process.

[0041] In step S2, the volume of the welding hole 11 and the volume of the pin 21 extending into the welding hole 11 are calculated by combining the measured size of the welding hole 11 and the size of the pin 21 of the plug-in 2 to obtain the theoretical volume required for welding, that is, the amount of solder V in the welding hole 11 after the pin 21 penetrates the welding hole 11 is calculated. t , solder volume V t Obtained by the following formula:

[0042] V t =(V2-V1+V)×2(Formula 1)

[0043] V2 is the volume of the inner cavity of the welding hole 11, V1 is the volume occupied by the pin 21 of the plug 2 extending into the welding hole 11, and V is the volume of the weld after the upper and lower solder pastes are connected. In some embodiments, if the welding hole 11 and the pin 21 are both cylindrical structures, their areas need to be calculated by analogy with cylinders. Therefore, the volume V2 of the inner cavity of the welding hole 11 and the volume occupied by the pin 21 of the plug 2 extending into the welding hole 11 are respectively obtained by the following formulas:

[0044] V2=π(D / 2) 2 H (Formula 3)

[0045] V1=π(d / 2) 2 L (Formula 4)

[0046] In Formula 3, D is the inner diameter of the soldering hole 11, and H is the thickness (or height) of the soldering hole 11; in Formula 4, d is the diameter of the pin 21, and L is the length of the pin 21 portion of the plug 2 extending into the soldering hole 11. It should be noted that in the actual production operation process, the volume V of the weld after the upper and lower solder pastes are connected can be ignored, so that the solder paste can be accurately controlled during welding.

[0047] In step S2, the solder column 4 is cylindrical in structure, and according to the obtained solder volume V t , so that the diameter of the solder column 4 is smaller than the welding hole 11. Preferably, the difference between the diameter of the solder column 4 and the diameter of the welding hole 11 is between 0.2 and 0.4 mm. The diameter of the solder column 4 is preset. In this embodiment, the diameter of the solder column 4 can be the same as the inner diameter of the welding hole 11. According to the preset diameter of the solder column 4 and the amount of solder V t , calculate the actual height of the solder column 4 of the same volume by analogy, according to the solder volume V t Calculate the height h of solder column 4. The height h of solder column 4 is obtained by the following formula:

[0048] h=V t / π(d1 / 2) 2 (Formula 2)

[0049] In Formula 2, d1 is the bottom diameter of the solder column 4. In some embodiments, the height h of the solder column 4 is 1.2 to 2.8 mm, and the weight accuracy of the solder column 4 is 0.001 g to minimize the impact on welding. t In the step of calculating the size of the solder column and making the solder column, after confirming the size of the solder column 4, solder paste is used to make the solder column 4. The composition of the solder column 4 is related to the product requirements. Sn is selected at low temperature. 62 Pb 36 Ag2 is used to make solder column 4, and Sn is used at high temperature. 96.5 Ag3Cu 0.5 The solder column 4 is made, and the melting point of the solder column 4 is the same as the melting point of the solder paste required by the product, so as to ensure that the solder column 4 can be equivalent to the product reflow soldering during the reflow process. In this way, it is convenient to make the required amount or more than the required amount of solder column 4 in advance before welding, so that the welding step can be directly entered when welding is needed, thereby greatly shortening the welding time and facilitating the operation. The solder column 4 can ensure the amount of solder, and ensure that the amount of solder paste or solder after welding can just fill the gap between the pin 21 and the welding hole 11, so as to improve the welding quality. The diameter of the solder column 4 is less than or equal to the inner diameter of the welding hole 11, so as to make the solder paste flow to the pin 21 and the welding hole 11 as much as possible during the reflow soldering process after melting, thereby reducing or even avoiding the solder paste flowing outside the welding hole 11 and increasing the cost, causing waste and failing to fill the welding hole 11 according to the preset situation.

[0050] According to step S3: This embodiment includes a clamp body 3, which is in a square block or rectangular parallelepiped structure. On one side of the clamp body 3 along the thickness direction, a placement groove 31 and a limiting groove 32 are coaxially opened in order from large to small along the thickness direction, so that there is a step between the placement groove 31 and the limiting groove 32. The substrate 1 with the welding hole position 11 is used to be installed in the placement groove 31, and a mounting hole 33 for the plug-in 2 to pass through is opened in the limiting groove 32 at a position corresponding to the welding hole position 11 along the thickness direction. The mounting hole 33 is a cylindrical hole, and the diameter of the mounting hole 33 is smaller than the diameter of the middle section 22 and larger than the diameter of the extension section 23, so that the extension section 23 can freely pass through the mounting hole 33 while the middle section 22 cannot pass through. In the present embodiment, since the substrate 1 has two columns (or two rows) of welding holes 11, the corresponding mounting holes 33 are arranged in two columns (or two rows). In order to facilitate the installation and removal of the substrate 1, an avoidance groove 34 is opened on the clamp body 3 and between the two columns (or two rows) of mounting holes 33 along the thickness direction of the clamp body 3. The avoidance groove 34 is coaxial with the limiting groove 32 and its width and length are both smaller than the width and length of the limiting groove 32. After the substrate 1 is installed in the placement groove 31, the substrate 1 can be taken out from the avoidance groove 34 along the thickness direction of the clamp body 3. After the plug-ins 2 are all welded, the plug-ins 2 can be taken out synchronously along the thickness direction through the avoidance groove 34. The installation and removal of the substrate 1 are more convenient. If it is necessary to fix the substrate 1, the substrate 1 can be contacted and adsorbed from the bottom surface of the clamp body 3 at the avoidance groove 34. Of course, the substrate 1 can also be pressed from the top surface of the substrate 1. For this reason, the avoidance groove 34 provides more options for fixing the substrate 1. In this embodiment, the clamp body 3 is made of hard metal such as hard aluminum to reduce the thermal melting of the clamp body 3 and facilitate heating and cooling during reflow.

[0051] In step S3, according to the steps of sequentially installing the plug-in, substrate and solder column on the clamp body, firstly, the prefabricated solder column 4 is coated with flux: the solder column 4 is immersed in the flux solution for 0 to 5 minutes and then taken out to ensure the solder joint value and avoid oxidation due to long immersion time, thereby ensuring the quality of the solder column 4. Preferably, the solder column 4 is immersed in the flux solution for 3 minutes and then taken out so that its surface is evenly coated with flux. The weight accuracy of the flux is controlled at 0.001g to minimize the influence of the flux on the solder column 4 and ensure the accuracy of the amount of solder paste. It should be noted that a highly active flux should be selected to remove oxides on the welding surface to ensure the quality of the welding joint. In this embodiment, the thickness or length of the middle section 22 is preferably equal to the groove depth of the limiting groove 32.

[0052] During assembly, the clamp body 3 is used to prepare the plug-in 2, the substrate 1 and the solder column 4 for welding. The extension sections 23 of each corresponding plug-in 2 are inserted into the mounting holes 33 from the top of the clamp body 3 in turn, so that the middle section 22 abuts against the bottom wall of the limiting groove 32. The mounting holes 33 are positioned by cooperating with the extension sections 23 and the middle section 22. The welding holes 11 on the substrate 1 are placed in the placement groove 31 from top to bottom corresponding to each plug-in 2. During the placement process, the pins 21 gradually penetrate into the corresponding welding holes 11 until the bottom surface of the substrate 1 abuts against the bottom surface of the placement groove 31. Since the length (height) of the middle section 22 is equal to the depth of the limiting groove 32, at this time, the The bottom surface contacts the top of the middle section 22 so that the substrate 1 can position the plug-in 2 after installation is completed to limit the freedom of the plug-in 2 in all directions. Finally, a corresponding number of solder columns 4 are placed on each pin 21. Since the length of the pin 21 is less than the depth of the welding hole 11, after the solder column 4 is placed, the bottom end of the solder column 4 and the pin 21 are both located in the welding hole 11. Since the flux has a certain viscosity and the volume and weight of the solder column 4 are relatively small, the flux is sufficient to adhere the solder column 4 to the top of the pin 21, so there is no need to fix the solder column 4 separately, thereby improving efficiency and reducing costs. In this way, the assembly of the substrate 1 and the plug-in 2 is completed.

[0053] In step S4, the assembled substrate 1 is placed into a reflow furnace along with the clamp body 3 for reflow soldering. During the reflow process, the solder column 4 melts under the action of the flux, and part of the solder melts and flows to the junction of the plug-in 2 and the inner wall of the welding hole 11. The remaining part of the solder covers the welding hole 11 where the top of the plug-in 2 is located. After cooling, the solder solidifies and the welding is completed.

[0054] In the step of cooling and solidifying until the solder column melts and fills the weld according to step S4, it also includes an inspector inspecting the substrate 1 after the welding has cooled. The inspector completes the appearance inspection of the substrate 1 by inspecting the solder joints at a magnification of 5 to 45 times using a microscope.

[0055] The difference between the method of controlling the welding of the solder hole plug-in by using prefabricated solder of the present invention and the prior art is that: the present invention is aimed at the reflow soldering process of the plug-in 2 at the welding hole 11 of the substrate 1 (printed circuit board), and for the plug-in component with the pin 21, the operator uses a professionally customized solder column 4 for reflow assembly to control the amount of solder used in the plug-in 2 at the welding hole 11, effectively reducing the undesirable defects of insufficient tin and excessive tin, and avoiding batch quality problems; the solder column 4 described in the present invention reduces the possibility of the non-solid components (such as volatile substances such as solvents and adhesives) forming an irregular sandwich structure inside the solder joint due to incomplete volatilization due to its special structure and stable solid content, and further effectively reduces the internal voids of the solder joint of the through-hole plug-in 2.

Claims

1. A method for controlling welding of a welding hole plug-in using prefabricated solder, characterized in that: The following steps are involved: S1. Dehumidification and drying: use an oven to dry the substrate; S2. Solder column production: Based on the original soldering holes on the substrate to be soldered, calculate the solder volume V between the soldering holes and the plug-in t , according to the solder volume V t Calculate the solder column size and make the solder column; S3, welding preparation: install the plug-in, substrate and solder column on the clamp body in sequence; S4, reflow soldering: Place the fixture assembled in step S3 in a reflow oven and start the operation until the solder column melts and fills the weld and then cools and solidifies.

2. The method for controlling welding of a welding hole plug by using prefabricated solder as claimed in claim 1, characterized in that: In the step S2, the part of the plug-in extending into the soldering hole is called the pin, and the solder amount V t Obtained by the following formula: V t =(V2-V1+V)×2(Formula 1) In formula (1), V2 is the volume of the inner cavity of the welding hole, V1 is the volume occupied by the pin of the plug-in extending into the welding hole, and V is the volume of the weld after the upper and lower solder pastes are connected; Where V2 = π(D / 2) 2 H, V1 = π(d / 2) 2 L, D are the inner diameters of the welding holes, H is the thickness of the welding holes, d is the pin diameter, and L is the length of the pin portion of the plug-in extending into the welding hole.

3. The method for controlling the welding of a welding hole plug by using prefabricated solder as claimed in claim 2, characterized in that: According to the solder volume V t The step of calculating the size of the solder column and making the solder column includes: t The solder column structure is cylindrical, so that the diameter of the solder column is smaller than the solder hole and the difference between the solder column diameter and the solder hole diameter is between 0.2 and 0.4 mm. Determine the solder column diameter; according to the solder volume V t The height h of the solder column is calculated, and the height h of the solder column is obtained by the following formula: h=V t / π(d1 / 2) 2 (Formula 2) In (Formula 2), d1 is the bottom diameter of the solder column.

4. The method for controlling welding of a welding hole plug by using prefabricated solder as claimed in claim 3, characterized in that: According to the solder volume V t The step of calculating the size of the solder column based on the value of and making the solder column also includes: after confirming the size of the solder column, using solder paste to make the solder column, selecting Sn at low temperature 62 Pb 36 Ag2 is used to make solder pillars, and Sn is used at high temperatures 96.5 Ag3Cu 0.5 Make solder pillars.

5. The method for controlling welding of a welding hole plug by using prefabricated solder as claimed in claim 4, characterized in that: According to the solder volume V t The step of calculating the size of the solder column based on the value of and making the solder column also includes: the melting point of the solder column is the same as the melting point of the solder paste required by the substrate.

6. The method for controlling welding of a welding hole plug by using prefabricated solder as claimed in claim 1, characterized in that: In the S3 step: it includes a clamp body, and a placement groove and a limit groove are coaxially opened in sequence from large to small along the thickness direction of the clamp body on one side surface of the clamp body, so that the placement groove and the limit groove are stepped, and a substrate with welding holes is used to be installed in the placement groove, and a mounting hole for the plug-in to pass through is opened in the limit groove at a position corresponding to the welding hole along the thickness direction.

7. The method for controlling welding of a welding hole plug by using prefabricated solder as claimed in claim 6, characterized in that: In the S3 step: the plug-in includes the pin, the middle section and the extension section in sequence along its axial direction, the diameter of the pin is smaller than the inner diameter of the welding hole, the diameter of the middle section is larger than the inner diameter of the welding hole and the diameter of the mounting hole respectively, and the diameter of the extension section is smaller than the diameter of the mounting hole; during assembly, the extension section is passed through the mounting hole from top to bottom, the middle section is located in the limiting groove, the pin extends into the welding hole, and the bottom end of the solder column and the pin are both located in the welding hole.

8. The method for controlling the welding of a welding hole plug by using prefabricated solder as claimed in claim 7, characterized in that: In the step S3: the height of the middle section is equal to the depth of the limiting groove, so that after assembly, the middle section abuts against the bottom wall of the limiting groove and the base plate respectively.

9. The method for controlling welding of a welding hole plug by using prefabricated solder as claimed in claim 8, characterized in that: In the step S3: before assembly, the surface of the solder column needs to be coated with flux: the solder column is immersed in the flux solution for 0 to 5 minutes and then taken out, and the weight accuracy of the flux is controlled at 0.001g; during assembly, the bottom of the solder column is placed on the top of the pin.

10. The method for controlling the welding of a welding hole plug by using prefabricated solder as claimed in claim 1, characterized in that: In the step S1, the drying temperature is 120±5° C. and the drying time is 1 to 4 hours.

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