DIP type filter through hole installation method

Abstract

The invention relates to the technical field of filter installation and application, in particular to a DIP type filter through hole installation method, which comprises the steps of preparing a printed board, trimming components and cleaning; a large-area grounding pad is arranged on the upper surface of the printed board, a non-welding mounting area is arranged on the grounding pad, and a through mounting hole is formed in the middle of the non-welding mounting area; a plurality of penetrating through holes are also formed in the grounding bonding pad, and the inner wall of each through hole is subjected to metallization electroplating treatment; soldering paste is applied to the grounding bonding pad, pins of the components are inserted into the mounting holes, and reflow soldering is carried out; after welding is completed, the printed board on which the components are fixed is cleaned; gaps between the component pins and the mounting holes are filled with glue for reinforcement; hooking and welding a winding inductor at the exposed end of the signal pin of the component, and welding the other end of the winding inductor on the printed board; wet absolute ethyl alcohol cotton balls are adopted for cleaning, then baking and drying are conducted, and assembling is completed; according to the invention, the problem of installation and fixation of the DIP type filter is solved.

Description

A method for mounting DIP type filter via through-hole Technical Field

[0001] This invention relates to the field of filter installation and application technology, and specifically to a method for mounting DIP type filter vias. Background Technology

[0002] Surface mount technology (SMT) has become the mainstream process in the electronics assembly industry since its development in the 1970s. However, in high-reliability applications, especially in military equipment, through-hole devices (THD / THT) still account for a considerable proportion as electronic products evolve towards multifunctionality and high performance. In actual printed circuit board (PCB) assembly, pure through-hole or pure surface mount designs are relatively rare; most adopt a hybrid layout where both coexist, and some complex boards even have through-holes and surface mount components distributed on both sides.

[0003] Among them, DIP-type metal housings are widely used in filter packaging manufacturing due to their cost and reliability advantages. However, currently, there is still a lack of clear and unified process standards for the high-reliability assembly of these devices. Especially in the installation specifications for aerospace electronic products, there are explicit requirements such as "metal-cased components should maintain reliable insulation from adjacent printed wires and conductor components" and "the installation of through-hole mounted components should not obstruct the full flow of solder into the metallized hole pads." Furthermore, large-mass components should not rely solely on silicone rubber for mechanical fixation. Therefore, it is evident that this type of metal-cased component presents numerous technological challenges in lead connection and mechanical fixation. Currently, customized mounting brackets are often required to meet assembly requirements, severely restricting the improvement of overall product assembly quality and production efficiency. Summary of the Invention

[0004] To address the above problems, this invention provides a method for mounting a DIP-type filter via a through-hole, comprising:

[0005] S1. Prepare the printed circuit board, trim and clean the component leads, wherein the component is a DIP filter to be installed; wherein, a large grounding pad is provided on the upper surface of the printed circuit board, and a non-soldering mounting area is provided on the grounding pad, and a through mounting hole is provided in the middle of the non-soldering mounting area; several through holes are also provided in the grounding pad, and the inner wall of each through hole is metallized by electroplating.

[0006] S2. Apply solder paste to the grounding pad by printing or dot coating, then insert the component leads into the mounting holes of the printed circuit board and place it in a reflow oven for reflow soldering to fix the component on the printed circuit board.

[0007] S3. After reflow soldering is completed, clean the printed circuit board with the components fixed on it to remove the flux;

[0008] S4. Use silicone rubber or epoxy to fill the gaps between component leads and mounting holes, and then cure to achieve reinforcement;

[0009] S5. Solder the exposed ends of the component pins with a wire-wound inductor and solder the other end of the wire-wound inductor to the printed circuit board to achieve a stable electrical connection.

[0010] S6. Clean the solder joints of the leads on the printed circuit board with a moistened cotton ball soaked in anhydrous ethanol to remove flux, and then bake in an 85°C oven for 10 minutes to dry, thus completing the assembly.

[0011] S7. By adjusting the layout and geometry of the wire-wound inductor at the component pins, the inductance value can be precisely adjusted, so that the performance parameters of the wire-wound inductor match those of the component, thereby improving the electrical properties of the component.

[0012] The beneficial effects of this invention are:

[0013] This invention proposes a standardized printed circuit board (PCB) mounting structure to achieve highly reliable through-hole mounting of non-axial metal-cased components, solving the problem of mounting and fixing non-axial metal-cased components. Specifically, a large-area grounding pad with several metallized through-holes on the PCB enables reflow mounting and fixing of the metal casing to the PCB (completed simultaneously with surface-mount components). Silicone rubber or epoxy is applied to the mounting holes to reinforce and protect the component through-hole leads. By soldering wire-wound inductors to the exposed ends of filter signal leads, signal transmission is achieved while adjusting the inductance value of the wire-wound inductors to improve the electrical performance of the filter. This invention eliminates the need for custom-made mounting brackets, and the component mounting and fixing method is highly reliable and simple, making it suitable for mass production. Attached Figure Description

[0014] Figure 1 shows the installation effect of the DIP-type filter in this invention;

[0015] Figure 2 is a partial enlarged view of the welding of components and wire-wound inductors in this invention;

[0016] In the diagram: 1. Grounding pad; 2. Non-soldering mounting area; 3. Solder; 4. Lead; 5. Wire-wound inductor; 6. Through hole; 7. Mounting hole; 8. Printed circuit board; 9. Filler adhesive; 10. Component. Detailed Implementation

[0017] 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.

[0018] This invention specification provides a method for mounting a DIP-type filter via a through-hole, as shown in Figures 1 and 2, including the following steps:

[0019] S1. Prepare the printed circuit board, trim and clean the component leads, where the component is a DIP filter to be installed.

[0020] In some embodiments, as shown in Figures 1 and 2, a large grounding pad 1 is provided on the upper surface of the printed circuit board 8. The grounding pad 1 is provided with a non-soldering mounting area 2. A through mounting hole 7 is provided in the middle of the non-soldering mounting area 2 to ensure that the pins 4 of the component 10 can be accurately passed through when it is tightly attached to the printed circuit board 8.

[0021] Furthermore, an array of through holes 6 are provided in the area of ​​the grounding pad 1. The inner wall of each through hole 6 is metallized and electroplated. The through holes 6 have a dual function: firstly, they can enhance the adhesion strength between the copper foil of the grounding pad and the printed circuit board substrate, thereby ensuring the stability of the component installation; secondly, during the reflow soldering process, they can help the gas generated by the evaporation of flux in the solder paste to be discharged smoothly, thereby reducing the soldering voids between the component and the grounding pad, and further improving the heat dissipation performance of the component.

[0022] It is important to note that the through-holes in the grounding pad serve only for pad reinforcement and flux evaporation and venting; they are not required for solder paste wetting and filling. Furthermore, the mounting holes do not require metallization plating.

[0023] In this embodiment of the invention, the area of ​​the grounding pad should be slightly larger than that of the component, thereby allowing excess solder paste at the bottom of the component to overflow, forming a climbing wetting angle and ensuring better soldering strength.

[0024] In some embodiments, the diameter of the mounting hole is 1-2 mm larger than the diameter of the component leads to facilitate subsequent colloid filling operations. Simultaneously, the diameter of the non-soldering mounting area is 1-2 mm larger than the diameter of the mounting hole to prevent solder from overflowing and entering the mounting hole, thus avoiding short circuits between the component leads and the component housing.

[0025] In some embodiments, the component leads are trimmed to ensure that when the component is mounted onto the printed circuit board, the length of its leads extending beyond the bottom surface of the printed circuit board is 2~5mm, which facilitates the implementation of subsequent lead wire bonding processes.

[0026] In some embodiments, the component leads are trimmed to the same length as the printed circuit board thickness. After the component leads are inserted into the mounting holes, they are flush with the bottom surface of the printed circuit board, with no exposed parts. At this time, the mounting holes on the printed circuit board are connected to the ground pad, and the mounting holes are metallized. Then, steps S2-S4 are performed to reflow soldering the component leads to the printed circuit board using solder paste, without the need for subsequent steps S5-S7 of wire-wound inductor hook soldering.

[0027] In some embodiments, a 3:1 mixture of acetone and gasoline is used to clean the trimmed components, followed by rinsing with anhydrous ethanol to ensure good solderability and effective adhesion to the potting compound.

[0028] In this invention, the component is a DIP-type filter with bottom leads, and its surface should have good solderability, preferably nickel-plated or gold-plated. The printed circuit board material is not limited and can be FR4, Rogers 5800, or other substrates. The solder paste material is not limited and can be the same as that used for other components on the printed circuit board.

[0029] S2. Apply solder paste to the grounding pad by printing or dot coating, then insert the component leads into the mounting holes of the printed circuit board and place it in a reflow oven for reflow soldering to fix the component on the printed circuit board.

[0030] In some embodiments, an appropriate amount of solder paste is applied to the grounding pad, except for the soldering mounting area and mounting holes, by printing or dotting. This ensures that the solder paste at the edge of the component forms a climbing wetting angle after reflow soldering, and that the solder penetration rate of the bottom pad of the component is not less than 80%. The selection of the application area and amount of solder paste must also ensure that there are no solder beads, solder dross, or other excess material in the mounting holes.

[0031] Furthermore, the method and timing of solder paste application can be consistent with the application method and timing of solder paste in other areas of the printed circuit board, simplifying the filter installation process.

[0032] Furthermore, select an appropriate reflow profile based on the chosen solder paste for reflow soldering to fully melt the solder paste and mount and fix the components onto the printed circuit board.

[0033] S3. After reflow soldering is completed, clean the printed circuit board with the components fixed on it to remove flux from the surface of the printed circuit board and the mounting hole area.

[0034] S4. Use silicone rubber or epoxy to fill the gaps between component leads and mounting holes, and then cure to achieve reinforcement.

[0035] In some embodiments, when silicone rubber or epoxy resin is used to fill the gap between component leads and mounting holes, the filling height shall not be less than 80% of the mounting hole, and the settling time shall not be less than 48 hours. Appropriate methods should be used for filling to ensure that the adhesive in the mounting hole is fully cured after filling, without defects such as peeling or bubbles.

[0036] It is important to note that a thorough inspection should be conducted before filling the mounting holes to ensure that there are no excess materials such as solder slag, solder balls, or flux present.

[0037] S5. Solder the exposed ends of the component pins with a wire-wound inductor and solder the other end of the wire-wound inductor to the printed circuit board to achieve a stable electrical connection.

[0038] In some embodiments, the wire-wound inductor is made of insulated wire with a diameter of 0.2 to 0.8 mm, and the number of turns between the inductor and the exposed end of the component pin is 1 to 3 to ensure connection strength.

[0039] The adjustable range of the wire-wound inductor's inductance value is selected based on the component's electrical characteristics. Precise matching of the inductance value can be achieved by adjusting the winding shape and the inductor's relative position within the filter. Appropriate inductor matching effectively improves the filter's noise suppression performance.

[0040] In some embodiments, when the filter can meet the signal filtering requirements without inductor parameter matching, its pins can be directly connected to the printed circuit board using silver wire or silver-plated copper wire with a diameter of 0.2~0.8 mm, without the need for soldering through wire-wound inductors.

[0041] In the embodiment of the present invention, when performing the lead wire bonding process, an electric soldering iron is used for soldering, and the solder is not limited.

[0042] S6. Clean the solder joints of the leads on the printed circuit board with a moistened cotton ball soaked in anhydrous ethanol to remove flux, and then bake in an 85°C oven for 10 minutes to dry, thus completing the assembly.

[0043] In particular, after the lead wires are soldered, soaking and cleaning are prohibited to avoid the cleaning medium from contaminating and damaging the adhesive filling the mounting holes.

[0044] Furthermore, after assembly, an inspection is conducted. If the test is passed, the product can proceed to the next production stage.

[0045] Furthermore, after the inductance adjustment is completed, a small amount of silicone rubber or epoxy glue can be applied to the gap between the wire-wound inductor body structure and the printed circuit board to improve the vibration resistance of the wire-wound inductor.

[0046] S7. By adjusting the layout and geometry of the wire-wound inductor at the component pins, the inductance value can be precisely adjusted, so that the performance parameters of the wire-wound inductor match those of the component, thereby improving the electrical properties of the component.

[0047] The components proposed in this invention are mounted and fixed to other components on the printed circuit board using the same reflow soldering process, offering advantages such as high connection strength, good grounding and heat dissipation performance, and eliminating the need for custom-made special brackets. After installation, the component leads are connected to the printed circuit board via a flexible connection, providing excellent vibration resistance. This design standardizes the layout of the printed circuit board, facilitating the widespread application and large-scale production of such components.

[0048] Furthermore, in some application scenarios with high requirements for filter performance, additional capacitor pads can be placed on the printed circuit board near the installation location. These pads, combined with the wire-wound inductors at the pins, form an LC filter circuit structure, thereby further improving key electrical performance indicators, including bandwidth and rectangular coefficient.

[0049] This invention achieves reflow soldering of components by setting a large-area grounding pad in the component mounting area of ​​the printed circuit board (PCB), and metallized through-holes are provided on the grounding pad to improve soldering strength. Simultaneously, mounting holes are provided within the grounding pad to ensure precise protrusion of component leads, and adhesive is subsequently applied to the gaps between the leads and the mounting holes on the PCB for reinforcement. Furthermore, wire-wound soldering is used at the exposed ends of the leads to achieve electrical signal connections, thereby enabling highly reliable mounting of non-axial components. This method offers a simple fixing mechanism. No special mounting brackets are required; it can be fixed simultaneously with surface-mount components during reflow soldering. The leads use wires for flexible connections to the PCB, and the gaps are filled with adhesive, resulting in high mounting reliability.

[0050] 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 a DIP-type filter via a through-hole, characterized in that, Includes the following steps: S1. Prepare the printed circuit board (PCB), trim and clean the component leads. The component is a DIP filter to be installed. The PCB has a large grounding pad on its upper surface, with a non-soldering mounting area and a through-hole in the center of the non-soldering mounting area. Several through-holes are also formed within the grounding pad, each with its inner wall metallized. S2. Apply solder paste to the grounding pad using printing or dot coating. Then, insert the component leads into the mounting holes on the PCB and place it in a reflow oven for reflow soldering to fix the component to the PCB. S3. After reflow soldering, clean the PCB with the fixed components. S4. Clean and remove flux from component leads; fill the gaps between component leads and mounting holes with silicone rubber or epoxy resin, then cure for reinforcement; S5. Hook-solder wire-wound inductors to the exposed ends of component leads and solder the other end of the wire-wound inductor to the printed circuit board for a stable electrical connection; S6. Clean the solder joints of the leads on the printed circuit board with a damp cotton ball soaked in anhydrous ethanol to remove flux, then bake in an 85°C oven for 10 minutes to dry, completing the assembly; S7. By adjusting the layout and geometry of the wire-wound inductor at the component leads, the inductance value can be precisely adjusted to match the performance parameters of the wire-wound inductor with the component, improving the electrical properties of the component.

2. The method for mounting a DIP-type filter via a through-hole according to claim 1, characterized in that, The diameter of the mounting hole is 1-2 mm larger than the diameter of the component pin, and the diameter of the non-soldering mounting area is 1-2 mm larger than the mounting hole.

3. The method for mounting a DIP-type filter via a through-hole according to claim 1, characterized in that, Trim the component leads to ensure that when the component is mounted on the printed circuit board, the lead extends 3-5 mm beyond the bottom surface of the printed circuit board.

4. The method for mounting a DIP-type filter via a through-hole according to claim 1, characterized in that, Wire-wound inductors are made of insulated wires, and the adjustable range of their inductance value is selected based on the electrical characteristics of the components.

5. The method for mounting a DIP-type filter via a through-hole according to claim 1, characterized in that, Apply an appropriate amount of solder paste to the grounding pads, except for the soldering mounting area and mounting holes, by printing or dotting. This will allow the solder paste at the edges of the components to form a climbing wetting angle after reflow soldering, and ensure that the solder penetration rate of the bottom pads of the components is not less than 80%.

6. The method for mounting a DIP-type filter via a through-hole according to claim 1, characterized in that, When using silicone rubber or epoxy to fill the gap between component leads and mounting holes, the filling height should not be less than 80% of the mounting hole, and the curing time should not be less than 48 hours.

7. The method for mounting a DIP-type filter via a through-hole according to claim 1, characterized in that, In step S1, the trimmed components are soaked and cleaned with a 3:1 mixture of acetone and gasoline, and then rinsed with anhydrous ethanol to ensure that the components have good solderability and effective adhesion to the potting compound.

8. A method for mounting a DIP-type filter via a through-hole according to claim 1, characterized in that, The wire-wound inductor is made of insulated wire with a diameter of 0.2~0.8mm, and the number of turns between the wire and the exposed end of the component pin is 1~3 to ensure the connection strength.

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