Circuit board reflow soldering structure

Abstract

The utility model discloses a circuit board reflow soldering structure. The circuit board reflow soldering structure comprises a circuit board body, a first material and a second material, a plurality of first through holes and second through holes are formed in the circuit board body; the circuit board body comprises a first plane and a second plane, the positions, close to the first through holes, of the first plane are coated with first welding layers, and the positions, close to the second through holes, of the first plane are pre-plated with second welding layers; the position, close to the second through hole, of the second plane is coated with a third welding layer. A pin of the first material penetrates through the first welding layer and is inserted into the first through hole; the pin of the second material penetrates through the third welding layer and is inserted into the second through hole, and the pin of the second material is also suitable for being connected with the second welding layer; wherein the first welding layer, the second welding layer and the third welding layer can be cooled after being heated and melted, so that the first material and the second material are mounted on the circuit board body. The structure saves the welding processing cost of the rear section, improves the production efficiency and improves the product quality.

Description

Technical Field

[0001] This utility model relates to the field of circuit board mounting technology, and specifically to a circuit board reflow soldering structure. Background Technology

[0002] With the rapid advancements in battery applications and the fast pace of technological development, BMS controllers and PCS inverters are also rapidly improving. In recent years, the related market has been expanding continuously, with the consumption and control of electrical energy showing exponential growth. PCBA, as a core component of the electronics manufacturing industry, is receiving increasing attention. Traditionally, through-hole components are still produced using wave soldering processes. For example, double-sided through-hole designs require spot soldering, selective soldering, or manual soldering. These processes are complex, increasing engineering costs. PCBA production involves multiple stages, leading to higher quality risks and lower efficiency. Therefore, the choice of soldering technology is crucial, directly impacting product quality, production efficiency, and cost. Utility Model Content

[0003] Therefore, the technical problem to be solved by this utility model is to overcome the shortcomings of traditional plug-in materials which are still produced by wave soldering process. For example, double-sided plug-in design requires spot welding, selective welding or manual soldering, etc., which are complex processes, increase engineering costs, and have many production links in PCBA with high quality risks and low efficiency. The choice of welding technology is crucial, as it directly affects the quality, production efficiency and cost of the product.

[0004] Therefore, this utility model provides a circuit board reflow soldering structure, comprising:

[0005] The circuit board body has a plurality of first through holes and second through holes; the circuit board body includes a first plane and a second plane, the first plane is coated with a first solder layer near the first through hole, and the first plane is pre-plated with a second solder layer near the second through hole; the second plane is coated with a third solder layer near the second through hole.

[0006] The first material has its pins inserted through the first solder layer into the first through hole;

[0007] The second material has its pins inserted through the third solder layer into the second through hole, and the pins of the second material are also adapted to be connected to the second solder layer.

[0008] The first welding layer, the second welding layer, and the third welding layer can be heated and melted, and then cooled to mount the first material and the second material onto the circuit board body.

[0009] Optionally, the cross-sectional area of ​​the first weld hole and the cross-sectional area of ​​the first weld layer are in a ratio of 1:3.

[0010] The cross-sectional area of ​​the second weld hole is 1:3 of the cross-sectional area of ​​the third weld layer.

[0011] Optionally, the thickness of the first welding layer and the third welding layer is 0.12-0.20 mm.

[0012] Optionally, the inner diameter of the second weld layer is smaller than the inner diameter of the second through hole, so that the second weld layer contacts the inner wall of the second through hole.

[0013] Optionally, the difference between the inner diameter of the second weld layer and the inner diameter of the second through hole is 0.05 mm.

[0014] Optionally, the distance between the extended surface of the pin end plane of the first material and the extended surface of the first plane is greater than or equal to 0.05 mm.

[0015] Optionally, the pin length of the second material is 3.0-3.5 mm.

[0016] Optionally, when the second material is fixed on the circuit board body, the length of the pin of the second material extending out of the second through hole is less than or equal to 1.5 mm.

[0017] Optionally, a red adhesive layer is further provided between the first material and the first plane.

[0018] Optionally, the circuit board body described above has a plurality of through holes, and at least some of the through holes are nested with a first through hole pad to form the first through hole;

[0019] Another portion of the via is nested with a second via pad to form the second via.

[0020] The technical solution provided by this utility model has the following advantages:

[0021] 1. The circuit board reflow soldering structure provided by this utility model includes: a circuit board body, a first material, and a second material; the circuit board body is provided with a plurality of first through holes and second through holes; the circuit board body includes a first plane and a second plane, the first plane is coated with a first solder layer near the first through hole, and the first plane is pre-plated with a second solder layer near the second through hole; the second plane is coated with a third solder layer near the second through hole; the pins of the first material pass through the first solder layer and are inserted into the first through hole; the pins of the second material pass through the third solder layer and are inserted into the second through hole, and the pins of the second material are also adapted to be connected to the second solder layer; wherein, the first solder layer, the second solder layer, and the third solder layer can be heated and melted and then cooled to install the first material and the second material on the circuit board body.

[0022] This solution uses a double-sided through-hole reflow method in SMT (Surface Mount Technology) to mount the first and second materials onto the circuit board body, replacing and eliminating subsequent processes such as spot soldering, wave soldering, selective soldering, and manual touch-up soldering. This saves on subsequent soldering costs, improves production efficiency, reduces uncontrollable risks to PCBA quality, and improves product quality.

[0023] 2. A first tin-coating hole is formed on the stencil corresponding to the first through-hole on the first plane. The ratio of the cross-sectional area of ​​the first through-hole (with its radial horizontal direction as the cross-section line) to the cross-sectional area of ​​the first tin-coating hole (with its radial horizontal direction as the cross-section line) is 1:3. This ratio can also be adjusted according to actual conditions. Several first tin-coating holes correspond to several first through-holes, covering the stencil on the first plane. A first solder layer, which is solder paste, is applied to the first through-holes using the first tin-coating holes. The first solder layer also covers part of the first plane around the first through-hole. The thickness of the solder paste is 0.12-0.20mm. With the above setup, when the first material is mounted on the circuit board body, such as... Figure 2 As shown, the pins of the first material pass through the first solder layer from top to bottom and are inserted into the first through hole, ensuring that the pins are soldered at least 75% after reflow.

[0024] 3. A second solder layer, which is a pre-plated tin layer, is pre-plated on the first plane near the second through-hole. The second solder layer is annular in shape and coaxially pre-plated on the second plane around the second through-hole. The outer diameter of the second solder layer is the same as that of the first solder layer, and its thickness is not limited. The inner diameter of the inner hole of the second solder layer is smaller than that of the second through-hole, so that the inner side of the second solder layer extends into the second through-hole and contacts the inner wall of the second through-hole. Specifically, the difference between the inner diameter of the second solder layer and the inner diameter of the second through-hole is 0.05mm, ensuring that a certain thickness does not affect the smooth passage of the pins on the second material. This effectively avoids the phenomenon of insufficient soldering of the pins after the first material is inserted due to the solder paste being carried away by the pins. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the circuit board body provided in this utility model, with the first plane facing upward and coated with the first solder layer.

[0027] Figure 2 This is a schematic diagram of the structure of the first material fixed on the circuit board body in this utility model.

[0028] Figure 3 This is a schematic diagram of the structure of the road plate body provided in this utility model, with the second plane facing upward and coated with a second welding layer and a third welding layer;

[0029] Figure 4 This is a schematic diagram of the structure in which the second material is fixed on the circuit board body according to the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1 – Circuit board body; 11 – First through-hole pad; 12 – First through-hole; 13 – Second through-hole pad; 14 – Second through-hole; 15 – First plane; 16 – Second plane;

[0032] 21 – First weld layer; 22 – Second weld layer; 23 – Third weld layer;

[0033] 31 – First material; 32 – Second material;

[0034] 4 - Red glue layer. Detailed Implementation

[0035] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0036] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0038] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0039] Example 1

[0040] This embodiment provides a circuit board reflow soldering structure, such as Figures 1 to 4 As shown, the circuit board body 1, the first material 31, and the second material 32 are included. The circuit board body 1 includes a first plane 15 and a second plane 16.

[0041] like Figures 1 to 4As shown, the circuit board has several through holes extending vertically where materials need to be inserted. A first through-hole pad 11 is nested within at least a portion of the through holes where the first material 31 needs to be installed. The first through-hole pad 11 is spool-shaped, meaning it is a hollow rod in the middle. The outer diameter of the hollow rod is equal to the inner diameter of the corresponding through hole. Larger diameter abutment rings are also provided on the outer edges of the upper and lower sides. The inner sides of the abutment rings are fixed to the hollow rod. The thickness between the two abutment rings is the same as the thickness of the circuit board body 1. When the first through-hole pad 11 is embedded in the corresponding through hole, the hollow... The outer wall of the rod is fitted to the inner wall of the through hole. The two end abutment rings near the hollow rod abut against the first plane 15 and the second plane 16 on the periphery of the through hole to fix the first through hole pad 11 in the corresponding through hole. The hollow channel in the middle of the hollow rod is the first through hole 12. The hollow rod, the first through hole 12 and the corresponding through holes are coaxially arranged. When the first material 31 is inserted, it can be accurately positioned to prevent radial deviation, which would cause the pin of the first material 31 to interfere with other components and prevent subsequent mechanical positioning failure. Similarly, at least a portion of the through-holes where the second material 32 needs to be installed contains a second through-hole pad 13. The second through-hole pad 13 is spool-shaped, meaning it is a hollow rod in the middle. The outer diameter of the hollow rod is equal to the inner diameter of the corresponding through-hole. Larger diameter abutment rings are provided on the outer edges of the upper and lower sides. The inner sides of the abutment rings are fixed to the hollow rod. The thickness of the two abutment rings is the same as the thickness of the circuit board body 1. When the second through-hole pad 13 is embedded in the corresponding through-hole, the outer wall of the hollow rod is fitted against the inner wall of the corresponding through-hole. Both ends of the abutting ring abut against the first plane 15 and the second plane 16 on the periphery of the through hole to fix the second through hole pad 13 in the corresponding through hole. The hollow channel in the middle of the hollow rod is the second through hole 14. Similarly, the hollow rod, the second through hole 14 and the corresponding through holes are coaxially arranged. When the second material 32 is inserted, it can be accurately positioned to prevent radial deviation, which would cause the pins of the second material 32 to interfere with other components and prevent subsequent mechanical positioning failure.

[0042] like Figures 1 to 2 As shown, a first tin-coating hole is formed on the stencil corresponding to the first through-hole 12 on the first plane 15. The ratio of the cross-sectional area of ​​the first through-hole 12 cut along its radial horizontal direction to the cross-sectional area of ​​the first tin-coating hole cut along its radial horizontal direction is 1:3. This ratio can also be adjusted according to actual conditions. Several first tin-coating holes correspond to several first through-holes 12, covering the stencil on the first plane 15. A first solder layer 21, which is solder paste, is applied to the first through-holes 12 using the first tin-coating holes. The first solder layer 21 also covers part of the first plane 15 around the first through-hole 12. The thickness of the solder paste is 0.12-0.20 mm. With the above configuration, when the first material 31 is mounted on the circuit board body 1, as... Figure 2 As shown, the pins of the first material 31 pass through the first solder layer 21 from top to bottom and are inserted into the first through hole 12 to ensure that the pins are soldered at least 75% after reflow.

[0043] The first plane 15 has a second solder layer 22 pre-plated near the second through hole 14. The second solder layer 22 is a pre-plated tin layer. The second solder layer 22 is generally annular and is pre-plated on the second plane 16 around the second through hole 14, coaxial with the second through hole 14. The outer diameter of the second solder layer 22 is the same as the outer diameter of the first solder layer 21, and the thickness is not limited. The inner diameter of the inner hole of the second solder layer 22 is smaller than the inner diameter of the second through hole 14, so that the inner side of the second solder layer 22 extends into the second through hole 14 and contacts the inner wall of the second through hole 14. Specifically, the difference between the inner diameter of the second solder layer 22 and the inner diameter of the second through hole 14 is 0.05mm, ensuring that the smooth passage of the pins on the second material 32 is not affected while maintaining a certain thickness.

[0044] like Figures 3 to 4 As shown, another stencil has a second tin-coating hole corresponding to the second through-hole 14. The ratio of the cross-sectional area of ​​the second through-hole 14 along its radial horizontal direction to the cross-sectional area of ​​the second tin-coating hole on the stencil along its radial horizontal direction is 1:3. This ratio can also be adjusted according to actual conditions. Several second tin-coating holes correspond to several second through-holes 14, covering the stencil onto the second plane 16. A second solder layer 22, also a solder paste, is applied to the second through-holes 14 using the second tin-coating holes. The second solder layer 22 also covers a portion of the second plane 16 around the second through-holes 14. The thickness of the second solder layer 22 is 0.12-0.20 mm. With the above settings, when the second material 32 is installed on the second plane 16, since the pins of the second material 32 are relatively long, when the pins of the second material 32 pass through the third solder layer 23 from top to bottom and are inserted into the first through hole 12, the tail end of the pins of the second material 32 can contact the inner wall of the second solder layer 22; ensuring the soldering area of ​​the pins on the second material 32 after reflow.

[0045] The specific soldering steps for the reflow soldering structure of the circuit board are as follows:

[0046] like Figures 1 to 4As shown, the circuit board body 1 is laid flat on the workbench, with the first plane 15 being the BOT surface, facing upwards. A steel plate with first tin-coating holes corresponding to the first through holes 12 is laid on the BOT surface. The first tin-coating holes and the first through holes 12 are coaxially aligned and correspond one-to-one. A first solder layer 21 is applied into the first tin-coating holes, covering the end of the corresponding first through hole 12 near the first plane 15 and the portion of the first plane 15 covering the outer periphery of the first through hole 12. A high-temperature resistant first material 31 is selected, requiring at least 256°C. The first material 31 is in conventional tape and reel packaging. Mylar sheets can be used above the first material 31 with notches, or there is a flat area for the pick-and-place machine to feed the material. The pins of the first material 31 are inserted through the first solder layer 21 and into the first through hole 12. By using a shim or other means, it is ensured that after insertion, the pin ends of the first material 31 are at least 0.05 mm away from the outside of the circuit board body 1. That is, the distance between the extended surface of the pin end plane of the first material 31 and the extended surface of the first plane 15 is at least 0.05 mm, preferably equal to 0.05 mm. By setting a certain distance between the pin ends of the first material 31 and the outside of the circuit board body 1, the protruding pins are prevented from affecting the subsequent production process.

[0047] After completing the above steps, the circuit board with the first material 31 inserted is placed in the soldering furnace with the first plane 15 facing upwards and heated. The first solder layer 21 is melted and then covered on the inner wall of the first through hole 12 and the pins of the first material 31 to fix the first material 31 on the circuit board body 1.

[0048] Next, with the first plane 15 facing upwards, a second solder layer 22 is pre-plated on the first plane 15 on the outer periphery of the second through hole 14. It is necessary to ensure that the inner side of the second solder layer 22 is pre-plated onto the inner wall of the second through hole 14 to effectively prevent the solder paste from being carried away by the pins when inserting the first material 31, resulting in insufficient solder on the pins after the boiler. After the pre-plating is completed, the circuit board body 1 is flipped over so that the second plane 16 faces upwards. The second plane 16 is the TOP surface. A steel plate with second soldering holes corresponding to the second through hole 14 is laid on the TOP surface. The second soldering holes on the steel plate are coaxially arranged in a one-to-one correspondence with the second through hole 14. A third solder layer 23 is applied into the second soldering holes. The third solder layer 23 covers the end of the corresponding second through hole 14 near the second plane 16 and covers the part of the second plane 16 on the outer periphery of the second through hole 14. A second material 32 with a lead length of 3.0-3.5mm is selected. The leads of the second material 32 are passed through the third solder layer 23 and inserted into the second through hole 14. The ends of the leads of the second material 32 pass through the second through hole 14 and extend to the bottom of the circuit board body 1. The side of the leads of the second material 32 contacts the inner wall of the second solder layer 22. Subsequently, the circuit board body 1 with the second material 32 inserted is placed in a soldering oven for heating and soldering. After being heated, the second solder layer 22 and the third solder layer 23 melt and cover the inner wall of the second through hole 14 and the leads of the second material 32. After cooling, the second material 32 is fixed to the circuit board body 1. After reflow soldering, the lead protruding from the circuit board body 1 by no more than 1.5mm, and the installation is completed.

[0049] This solution replaces or eliminates subsequent processes such as spot soldering, wave soldering, selective soldering, and manual soldering by using double-sided through-hole reflow soldering, saving downstream soldering costs, improving production efficiency, reducing uncontrollable risks to PCBA quality, and improving product quality.

[0050] Before the second soldering process, a layer of red adhesive 4 needs to be sprayed between the first plane 15 and the first material 31. One end of the red adhesive layer 4 is connected to the first plane 15, and the other end is connected to the first material 31 to fix the position between the first material 31 and the circuit board body 1. This prevents the first material 31 from falling off due to the melting of the solder between the first material 31 and the first through hole 12 during the second soldering process.

[0051] Finally, the circuit board body 1, after the installation of the first material 31 and the second material 32, needs to be inspected and tested using AOI equipment. Compared to existing defect testing methods, this solution optimizes the existing manual and visual inspection into equipment-based inspection of soldering yield. Compared to manual visual inspection, this improves PCBA inspection efficiency and reduces the rate of defects caused by human error. After inspection, corresponding inspection records can be automatically generated, reducing the workload of personnel.

[0052] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A circuit board reflow soldering structure, characterized in that, include: The circuit board body (1) has a plurality of first through holes (12) and second through holes (14); the circuit board body (1) includes a first plane (15) and a second plane (16), the first plane (15) near the first through hole (12) is coated with a first solder layer (21), and the first plane (15) near the second through hole (14) is pre-plated with a second solder layer (22); the second plane (16) near the second through hole (14) is coated with a third solder layer (23); The first material (31) has its pins inserted through the first solder layer (21) into the first through hole (12); The second material (32) has its pins inserted through the third solder layer (23) into the second through hole (14), and the pins of the second material (32) are also adapted to be connected to the second solder layer (22); The first welding layer (21), the second welding layer (22) and the third welding layer (23) can be heated and melted and then cooled to mount the first material (31) and the second material (32) onto the circuit board body (1).

2. The circuit board reflow soldering structure according to claim 1, characterized in that, The cross-sectional area of ​​the first weld hole: the cross-sectional area of ​​the first weld layer (21) = 1:3; The cross-sectional area of ​​the second weld hole is 1:3 of the cross-sectional area of ​​the third weld layer (23).

3. The circuit board reflow soldering structure according to claim 1, characterized in that, The thickness of the first welding layer (21) and the third welding layer (23) is 0.12-0.20 mm.

4. The circuit board reflow soldering structure according to claim 1, characterized in that, The inner diameter of the second weld layer (22) is smaller than the inner diameter of the second through hole (14) so ​​that the second weld layer (22) contacts the inner wall of the second through hole (14).

5. The circuit board reflow soldering structure according to claim 3, characterized in that, The difference between the inner diameter of the second weld layer (22) and the inner diameter of the second through hole (14) is 0.05 mm.

6. The circuit board reflow soldering structure according to claim 5, characterized in that, The distance between the extended surface of the pin end plane of the first material (31) and the extended surface of the first plane (15) is greater than or equal to 0.05 mm.

7. The circuit board reflow soldering structure according to claim 6, characterized in that, The pin length of the second material (32) is 3.0-3.5 mm.

8. The circuit board reflow soldering structure according to claim 7, characterized in that, When the second material (32) is fixed on the circuit board body (1), the length of the pin of the second material (32) extending out of the second through hole (14) is less than or equal to 1.5 mm.

9. The circuit board reflow soldering structure according to claim 8, characterized in that, A red adhesive layer (4) is also provided between the first material (31) and the first plane (15).

10. The circuit board reflow soldering structure according to any one of claims 1-9, characterized in that, The circuit board body (1) has several through holes, and at least some of the through holes are nested with first through hole pads (11) to form the first through hole (12); Another portion of the via is nested with a second via pad (13) to form the second via (14).

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