Mounting and welding method for SMT-compatible DIP component

Abstract

The invention relates to the technical field of DIP component installation, in particular to an SMT compatible DIP component installation and welding method, which comprises the following steps of: processing a DIP component pin by adopting a pin forming die, so that the DIP component pin is bent outwards, and then cutting a bent section of the DIP component pin; coating soldering paste on the surface of the bonding pad of the printed circuit board, and mounting the DIP component to a corresponding position to ensure that the bent section of the pin of the DIP component is in full contact with the soldering paste on the bonding pad; the printed circuit board on which the DIP component is attached is placed in a reflow oven for reflow soldering, and soldering flux cleaning is carried out after reflow soldering is completed; a gap between the DIP component main body and the printed board is filled with a first colloid, and then the periphery or four corners of the DIP component are dispensed with a second colloid; according to the invention, plug-in components are converted into surface-mounted components, so that the space utilization rate of the printed board is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of DIP component mounting technology, and more specifically to an SMT-compatible DIP component mounting and soldering method. Background Technology

[0002] As electronic products continue to evolve towards miniaturization, multifunctionality, and high performance, the component density on printed circuit board (PCB) assemblies is constantly increasing, and assembly processes are primarily based on surface mount technology, with reflow soldering being a common practice. However, military products have stringent requirements for the high reliability and multifunctionality of PCB assemblies. Therefore, a certain number of through-hole components, such as dual in-line packages (DIPs), are still used in the design. Some PCBs even have both through-hole and surface mount components on both the front and back sides. The differences in their mounting and soldering methods pose significant challenges to the production efficiency and quality control of PCB assemblies.

[0003] Currently, the assembly process for mixed-assembly printed circuit board assemblies typically involves first reflow soldering surface mount components, followed by manual soldering of through-hole components. This increases the number of turnover steps in the production process, extends the processing cycle, and makes it difficult to effectively control soldering quality. Furthermore, in the manual or wave soldering processes commonly used for through-hole components, the through-hole filling performance of the solder has always been a key technical challenge for double-sided and multilayer boards, especially in lead-free soldering processes. In some cases, if through-hole components are surface mount mounted, the bottom of the through-hole component may block the through-hole leads, forming a blind via structure. This easily leads to insufficient solder penetration and the formation of closed air cavities at the lead roots. Such poor filling not only reduces the mechanical strength of the solder joint but also weakens its thermal fatigue resistance and can even seriously affect the electrical performance of the product. Summary of the Invention

[0004] To address the above problems, this invention provides an SMT-compatible DIP component mounting and soldering method, comprising the following steps:

[0005] S1. Use a lead trimming fixture to process the leads of the DIP component, so that the two leads of the DIP component are bent outward;

[0006] S2. Print solder paste on the soldering side of the printed circuit board and attach the bent sections of the DIP component leads, then put it into the reflow oven for reflow soldering, and clean it after soldering is completed;

[0007] S3. Fill the gap between the DIP component body and the printed circuit board with the first adhesive, and then apply the second adhesive around the DIP component or at the four corners.

[0008] The beneficial effects of this invention are:

[0009] Converting through-hole components to surface-mount components effectively improves the space utilization of printed circuit boards (PCBs), simplifies PCB assembly processes, and increases production efficiency. Surface-mount components are more likely to form high-quality solder joints, helping to ensure process pass rates and thus guaranteeing PCB assembly quality. Reinforcing the component body through dispensing enhances the vibration resistance of the mounting solder joints, resulting in higher overall reliability of the mounting structure. Furthermore, this invention provides a lead forming mold, ensuring that the above processes can be implemented easily and with high quality, suitable for mass production applications. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the pin forming mold according to an embodiment of the present invention;

[0011] Figure 2 This is a schematic diagram of the DIP component mounting and soldering of the present invention;

[0012] Figure 3 This is a schematic diagram of the fixture on the pin forming mold of the present invention. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] This invention provides a surface mount technology (SMT) compatible DIP component mounting and soldering method, aiming to solve problems such as complex processes, numerous product turnover steps, low efficiency, and difficulty in ensuring quality consistency in the mounting and soldering of through-hole components in mixed-assembly printed circuit board production. By designing a dedicated tooling fixture, the leads of DIP through-hole components are shaped to adapt to surface mount process requirements, thereby achieving highly reliable mounting and soldering. This solution features high efficiency, low cost, high reliability, and strong product applicability, making it suitable for large-scale mass production.

[0015] This invention specification provides a method for mounting and soldering SMT-compatible DIP components using some embodiments, such as... Figures 1-3 As shown, it specifically includes:

[0016] S1. Use a lead forming mold to process the DIP component leads, causing the DIP component leads to bend outwards, and then trim the bent sections of the DIP component leads.

[0017] In some embodiments, such as Figures 2-3 As shown, the pin forming mold includes a base and an upper clamp; the base has a rectangular guide groove in the middle, and a concave structure is machined inside the rectangular guide groove. The diameter of the concave structure is smaller than the opening of the rectangular guide groove, thereby forming an annular step surface between the top surface of the concave structure and the inner wall of the rectangular guide groove; wherein, the shape of the concave structure is the same as the shape of the DIP component body; the upper clamp is a rectangular plate, which has multiple sets of through channels inside; each set of channels consists of two mirror-symmetrical channels on the left and right, wherein the left channel starts from the left edge of the rectangular plate, extends inward horizontally first, and then turns downward; the right channel starts from the right edge of the rectangular plate, also extends inward horizontally first, and then turns downward.

[0018] Specifically, the width of each channel in the upper fixture is equal to the diameter of the DIP component pin.

[0019] Specifically, the thickness of the upper clamp is at least twice the diameter of the DIP component lead, or at least greater than 0.75 mm, to avoid accidental damage to the DIP component body caused by stress generated during the molding process.

[0020] Specifically, the width of the upper clamp should be slightly smaller than the width of the rectangular guide groove of the base to ensure that it can be embedded in the base to form a stable limiting structure.

[0021] The flat plate design of the upper clamp can, on the one hand, ensure a reasonable gap between the DIP component body and the bending section during the pin forming process, thereby protecting the pin and its root insulator from damage; on the other hand, the flat plate also has the dual process functions of cutting and positioning and stamping boss formation.

[0022] In some embodiments, processing the leads of DIP components using a lead forming die includes:

[0023] Place the DIP component upside down into the base so that the body of the DIP component fits into the concave structure, and the pins of the DIP component are facing upwards.

[0024] Align the channel of the upper clamp with the pin of the DIP component and insert it. Ensure that the upper clamp is stably placed in the rectangular guide groove of the base, so that it contacts the annular step surface and fits tightly against the upper edge of the rectangular guide groove. At this time, each pin of the DIP component is at the end of the corresponding channel.

[0025] A stamping and cutting tool is used to press the DIP component leads downwards, bending each lead from the inside out, and simultaneously cutting off the excess bent portion. This ensures that the bending length of each DIP component lead corresponds to the pad size, meeting the installation and soldering process requirements of surface mount components.

[0026] After the stamping and cutting are completed, the upper fixture is slowly moved down along the rectangular guide groove until the bent section of the DIP component lead is completely aligned and fits with the horizontal section of the corresponding channel. At this point, the upper fixture can be easily removed, and the formed DIP component can be taken out.

[0027] In particular, the stamping cutting tool is the lead forming cutting unit in the existing stamping cutting mechanism. It can adopt an integrated structure that integrates stamping and cutting functions, or a separate structure in which stamping and cutting are independent.

[0028] Specifically, the bending length of the DIP component lead should be 3 to 5 times the diameter of the DIP component lead to ensure sufficient soldering strength.

[0029] S2. Apply solder paste to the surface of the printed circuit board pads and mount the DIP components to the corresponding positions, ensuring that the bent sections of the DIP component leads are in full contact with the solder paste on the pads.

[0030] In some embodiments, after obtaining the formed DIP component in step S1 and before proceeding to step S2, the component needs to undergo heat treatment, including: placing the DIP component in a reflow oven and setting the same reflow time and temperature as during installation in the subsequent step S3; after reflow, baking the DIP component in an oven at 120~140℃ for 120 minutes; after baking, checking whether the bent section of the DIP component pin remains horizontal; if there is springback, using a pin forming mold to perform secondary shaping of the pin.

[0031] In some embodiments, the pad position corresponding to the bent section of the DIP component pin does not need to be strictly limited to directly below the DIP component body; it can extend appropriately outward to ensure that the solder joint is in a state that is easy to observe and inspect. If installation space is limited, to save layout area, the pad can also be placed below the DIP component body, but sufficient overlap length must be ensured to ensure soldering reliability. In addition, in certain cases, the vertical extension length of the DIP component pin can be appropriately increased, for example, by thickening the upper clamp to raise the component mounting height. This allows low-profile components to be arranged directly below the DIP component body, thereby further improving the surface space utilization of the printed circuit board.

[0032] S3. Place the printed circuit board with DIP components into the reflow oven for reflow soldering, and clean the flux after reflow soldering.

[0033] In some embodiments, after the components are installed, appropriate methods should be used to remove flux residue and other excess material from the surface of the printed circuit board.

[0034] S4. Fill the gap between the bottom surface of the DIP component and the printed circuit board with the first adhesive.

[0035] In some embodiments, a first colloid is injected into the gap between the DIP component body and the printed circuit board to achieve reinforcement. The first colloid has a low viscosity, high fluidity and low stress formulation, and silicone rubber is preferred.

[0036] S5. Apply a second colloid around the perimeter or corners of the DIP component.

[0037] In some embodiments, after completing the first colloid filling in step S4, a second colloid is applied around the DIP component to cover the first colloid, or a second colloid is applied to the four corners of the DIP component to perform a strengthening treatment, thereby further enhancing the vibration resistance of the solder joint and ensuring that the installation reliability is fully guaranteed.

[0038] Specifically, a high-strength epoxy adhesive is selected as the second colloid. When applying high-strength epoxy adhesive around the perimeter or corners of DIP components, care should be taken to avoid contaminating or covering the pin pads and solder joints with the high-strength epoxy adhesive, in order to prevent stress from damaging the solder joints during the curing process.

[0039] In some embodiments, after the first colloid is dispensed, it needs to stand for at least 48 hours to ensure that the first colloid is fully cured; the second colloid dispensing operation can only be carried out after the first colloid at the bottom has been fully cured.

[0040] Specifically, the length of the upper clamp is less than the length of the guide groove.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "rotation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for mounting and soldering SMT-compatible DIP components, characterized in that, Includes the following steps: S1. Use a lead forming mold to process the DIP component leads, making the DIP component leads bend outwards, and then trim the bent section of the DIP component leads. S2. Apply solder paste to the surface of the printed circuit board pads and mount the DIP components to the corresponding positions, ensuring that the bent sections of the DIP component leads are in full contact with the solder paste on the pads; S3. Place the printed circuit board with DIP components into the reflow oven for reflow soldering, and clean the flux after reflow soldering. S4. Fill the gap between the bottom of the DIP component and the printed circuit board with the first adhesive to reinforce the solder joint; S5. Apply a second adhesive around the perimeter or corners of the DIP components for overall reinforcement.

2. The SMT-compatible DIP component mounting and soldering method according to claim 1, characterized in that, The pin forming mold includes a base and an upper clamp; the base has a rectangular guide groove in the middle, and a concave structure is machined inside the rectangular guide groove. The diameter of the concave structure is smaller than the opening of the rectangular guide groove, thereby forming an annular step surface between the top surface of the concave structure and the inner wall of the rectangular guide groove; wherein, the shape of the concave structure is the same as the shape of the main body of the DIP component; the upper clamp is a rectangular plate, which has multiple sets of through channels inside; each set of channels consists of two mirror-symmetrical channels on the left and right, wherein the left channel starts from the left edge of the rectangular plate, extends inward horizontally first, and then turns downward; the right channel starts from the right edge of the rectangular plate, also extends inward horizontally first, and then turns downward.

3. The SMT-compatible DIP component mounting and soldering method according to claim 2, characterized in that, The use of lead forming dies to process the leads of DIP components includes: Place the DIP component upside down in the base so that the body of the DIP component fits into the concave structure; Align the channel of the upper clamp with the pins of the DIP component and insert it. Ensure that the upper clamp is stably placed in the rectangular guide groove of the base, so that it contacts the annular step surface and fits tightly against the upper edge of the rectangular guide groove. At this time, each pin of the DIP component is at the end of the corresponding channel. The DIP component leads are pressed downwards using a stamping and cutting tool, causing each lead to bend outwards, and the excess bent portion is cut off simultaneously. After the stamping and cutting are completed, the upper fixture is slowly moved down along the rectangular guide groove until the bent section of the DIP component pin is completely aligned and fits with the horizontal section of the corresponding channel, so that the upper fixture can be smoothly released and the formed DIP component can be taken out.

4. The SMT-compatible DIP component mounting and soldering method according to claim 2, characterized in that, The thickness of the upper clamp is at least twice the diameter of the DIP component lead, or at least greater than 0.75 mm.

5. The SMT-compatible DIP component mounting and soldering method according to claim 1, characterized in that, After obtaining the formed DIP component in step S1, before proceeding to step S2, the component needs to undergo heat treatment, including: placing the DIP component in a reflow oven and setting the same reflow time and temperature as during installation in step S3; after reflow, baking the DIP component in an oven at 120~140℃ for 120 minutes; after baking, checking whether the bent section of the DIP component lead remains horizontal. If there is springback, the lead is reshaped using a lead forming mold.

6. The SMT-compatible DIP component mounting and soldering method according to claim 1, characterized in that, The bending length of the DIP component lead should be 3 to 5 times the diameter of the DIP component lead.

7. The SMT-compatible DIP component mounting and soldering method according to claim 1, characterized in that, The first colloid is made of soft silicone rubber.

8. The SMT-compatible DIP component mounting and soldering method according to claim 1, characterized in that, The second colloid is made of high-strength epoxy resin.

Images