Lossless desoldering method for LCC packaging optical module

Abstract

The invention discloses a lossless desoldering method for an LCC packaging optical module, and solves the problems of high desoldering difficulty and excessive dependence on the skill level of an operator caused by the problems of high dimensional precision requirement, more desoldering time limitation, large influence of inconsistency of welding spots and the like of a desoldering device in the prior art. The basic implementation principle of the invention is as follows: 1, pre-cleaning an LCC packaging optical module to be desoldered; 2, the cleaned exposed welding spots are coated with heat conduction cement gum, so that the heat conduction cement gum is tightly attached to the exposed welding spots; 3, an unwelding tool is obtained, the unwelding tool comprises a heating frame, heating holes located in the peripheral side of the heating frame and temperature control soldering iron matched with the heating holes in size, the shape of the heating frame is matched with the shape of the LCC packaging optical module, the heating frame is arranged on the periphery of the heat conduction cement, and the heating frame is tightly attached to the heat conduction cement; 4, a temperature control soldering iron is placed in the heating hole, and soldering tin is heated; 5, heating until the solder is molten, and clamping the LCC packaging optical module; and 6, the heat-conducting cement gum is cleaned, and lossless desoldering is completed.

Description

Technical Field

[0001] The present invention relates to a method for desoldering an optical module, and more particularly to a method for non-destructively desoldering an LCC package optical module. Background Art

[0002] The LCC package optical module belongs to the optoelectronic device among components, and is widely used in short-distance high-speed data communication connections and parallel optical interconnection fields such as optical backplane transmission, interconnection between servers and storage arrays, and radar processors. Although the design, manufacturing, and application levels of LCC package optical modules have been steadily improved, it is still impossible to ensure 100% qualification after being soldered to a circuit board. In the military electronics field, component failures often occur due to problems in the component's own design and manufacturing, or application design and production processes. Usually, after a component fails, it is necessary to perform a failure analysis on the faulty component, locate the cause of the failure, determine the failure mode, and understand the failure mechanism, and then take effective measures to improve the production quality of the component and the circuit board-related products after installation.

[0003] Therefore, in the process of performing a failure analysis on a faulty LCC package optical module, it is crucial to first ensure how to desolder the LCC package optical module without damage.

[0004] As Figure 1 shown, an LCC package optical module generally includes main components such as a PCB board C, a bracket B, a cover plate A, and an optical fiber D. Since the LCC package optical module has a built-in pigtail MT interface, its heat-resistant temperature requirement is less than 100 °C. Excessive temperature will not only damage the pigtail, but also affect the stability of the LCC package optical module's housing sealant and internal components. Therefore, when desoldering an LCC package optical module without damage, overall heating methods such as a heating table, a rework station, wave soldering, and reflow soldering cannot be used, and only the method of heating all solder joints with a soldering iron tip and then desoldering can be adopted.

[0005] However, if the operation time of this local heating desoldering method is too long, it will also cause component damage, or problems such as solder pad bulging and substrate white spots due to overheating of the PCB board.

[0006] In the prior art, there is also a method of adaptively adjusting the shape of the soldering iron tip to make the soldering iron tip fit around the LCC packaged optical module. Using this specific shape of the soldering iron tip, with solder as a thermal bridge, the solder joints on the four sides of the LCC packaged optical module are heated and desoldered. For example, Chinese utility model patent CN216882161U discloses a desoldering device for an LCC packaged optical module, including a heating frame, a guide rail and a heating body. The heating body is mounted on the heating frame. The heating frame is connected to the guide rail through a tension spring. When stress is applied, the heating frame can move in the guide rail. When the stress is stopped, the heating frame can return to its original position. When the desoldering device is used for desoldering operations, pre-alignment of the optical module can be achieved, and the actual desoldering can be completed within 5-10 seconds, avoiding damage to the optical module due to long-term heating and reducing the risk of disassembly.

[0007] However, since LCC packaged optical modules are usually manually soldered, the morphology of the solder joints is often closely related to the size of the pad, the diameter of the solder, the size of the soldering iron, the skill level of the operator, etc., which will lead to different sizes of solder joints and poor consistency. The methods of desoldering using the above-mentioned desoldering device are all hard contact heating methods, that is, directly using the above-mentioned desoldering device to heat the solder joints. Therefore, there is a problem that the size of the desoldering device may not be compatible with the size of the LCC packaged optical module to be desoldered.

[0008] When the size of the above-mentioned desoldering device is larger than the size of the LCC packaged optical module to be removed, it is often impossible to heat all solder joints at the same time, so that during the desoldering process, the desoldering device needs to be constantly moved back and forth, left and right, so that all solder joints can be melted at a certain moment. However, due to the different sizes of solder joints, the large solder joints will melt first, and then they will contact the small solder joints, and finally all solder joints can be molten. This operation invisibly increases the desoldering time. Once the solder joints are heated for too long (about 30s or more), it will cause irreparable problems such as the solder pads warping, falling off, or discoloration of the PCB board, which will damage the solder pads or affect the failure analysis of faulty components in the LCC packaged optical module.

[0009] When the size of the desoldering device is smaller than or equal to the size of the LCC packaged optical module to be removed, it is difficult to smoothly fit around the LCC packaged optical module to be removed, or even impossible to fit at all, resulting in the LCC packaged optical module being unable to be desoldered smoothly.

[0010] At the same time, the above desoldering method also requires melting a large amount of solder to ensure that the solder joints can be melted. However, a large amount of molten solder will cause the solder joints of the LCC package optical module to bridge after desoldering, and a soldering iron needs to be used for secondary heating to clean the bridged solder joints, increasing the risk of rework of the LCC package optical module.

[0011] In summary, due to the high dimensional accuracy requirements of existing desoldering equipment, many desoldering time restrictions, and the great influence of solder joint inconsistency, desoldering is difficult and overly dependent on the skill level of the operator. Summary of the invention

[0012] The purpose of the present invention is to solve the technical problems in the prior art such as high dimensional accuracy requirements for desoldering devices, multiple desoldering time restrictions, and great influence of solder joint inconsistency, which lead to great difficulty in desoldering and excessive reliance on the skill level of operators, and to provide a non-destructive desoldering method for LCC packaged optical modules.

[0013] In order to achieve the above object, the present invention adopts the following technical solution:

[0014] A non-destructive desoldering method for an LCC packaged optical module is special in that it comprises the following steps:

[0015] S1, cleaning the attachments on the exposed solder joints of the LCC package optical module to be desoldered, so that the solder on the exposed solder joints is exposed to the air;

[0016] S2, applying a circle of thermal conductive adhesive on the cleaned exposed solder joints, so that the thermal conductive adhesive is closely attached to the exposed solder joints;

[0017] S3, after the thermal conductive glue is applied, obtain a desoldering tool, which includes a heating frame, heating holes located around the heating frame, and a temperature-controlled soldering iron that matches the size of the heating holes. The shape of the heating frame matches the shape of the LCC packaged optical module to be desoldered, and the heating frame can be placed on the periphery of the thermal conductive glue so that the inner wall of the heating frame is tightly fitted with the thermal conductive glue;

[0018] S4, installing a desoldering tool, placing a heating frame on the periphery of the thermal conductive paste, and after the desoldering tool is installed, placing the temperature-controlled soldering iron in the heating hole;

[0019] S5, wait for the temperature-controlled soldering iron to rise to a set temperature, heat the solder, add the solder, and heat it to a molten state, and continue to heat the heating frame with the molten solder for a set time, so that the solder of the exposed solder joint is in a molten state;

[0020] S6, moving the temperature-controlled soldering iron to separate it from the heating hole, using tweezers to clamp the LCC packaged optical module and the desoldering tool in sequence and remove them, cleaning the thermal conductive glue, and completing the desoldering of the LCC packaged optical module.

[0021] Using a malleable thermal conductive putty as a heat bridge, apply the thermal conductive putty to the exposed solder joints and press the thermal conductive putty to ensure full contact between the thermal conductive putty and the exposed solder joints. Then, make the heating frame of the desoldering tooling contact with the thermal conductive putty. Use a temperature-controlled soldering iron to raise the temperature of the heating frame, and then conduct heat through the thermal conductive putty to the solder at the exposed solder joints. When the solder reaches the molten state, stop heating, remove the LCC package optical module and the desoldering tooling, and clean the thermal conductive putty, thus completing the desoldering. Since the thermal conductive putty has insulation properties, it forms a relatively enclosed space around the solder joints. During the desoldering process, there will be no bridging phenomenon of the component solder joints, avoiding the need for secondary heating to remove tin and clean the solder joints and components after desoldering, and improving the desoldering quality. Moreover, the thermal conductive putty wraps the solder, heating the solder more fully, improving the heating efficiency, and shortening the heating time.

[0022] Further, in step S3, one side of the heating frame has an opening to enable the optical fiber of the LCC package optical module to pass through;

[0023] At least two bosses are further provided on the outer peripheral wall of the heating frame, and one of the heating holes is respectively provided at the top of each boss.

[0024] Design an opening structure to lead out the optical fiber and avoid the heating frame heating the optical fiber. Excessively high heating temperature will damage the optical fiber. And this structural design makes the entire desoldering tooling smaller in size, which can minimize the interference between the LCC package optical module and the surrounding non-desoldering parts. Design at least two bosses for opening the heating holes to make the heat conduction more uniform and improve the heating efficiency.

[0025] Further, in step S3, the heating frame is circumferentially divided into at least two parts by mass, and each part has a centroid, and the boss is provided at the centroid. Setting the boss at the centroid is used to carry the temperature-controlled soldering iron, which can improve the efficiency of heat conduction and enhance the heating uniformity of the heating frame.

[0026] Further, in step S3, the heating frame is divided into three parts by mass. The three-equal-part structure is the most reasonable and has the highest heat conduction efficiency.

[0027] Further, in step S3, the material of the heating frame is copper. Copper has good thermal conductivity, is easy to process and has a low cost.

[0028] Further, in step S3, the upper part of the heating frame is in the shape of a square straight cylinder, and the lower part is in the shape of a square tapered cylinder. The large end of the square tapered cylinder is connected to the lower end of the square straight cylinder. The square straight cylinder and the square tapered cylinder respectively form the heating part and the desoldering part of the heating frame, and the boss is provided on the outer peripheral wall of the square straight cylinder. The funnel-shaped structural design can reduce the area occupied by the bottom of the heating frame during desoldering and reduce the impact on the non-desoldering parts of the LCC package optical module.

[0029] Further, in step S3, when installing the desoldering tooling, place the square conical tube of the heating frame (1) on the pads of the PCB of the LCC package optical module to be desoldered, and make the minimum distance between its inner wall surface and the solder on the exposed solder joints be h2. The minimum distance between the inner wall of the square straight tube and the outer peripheral wall of the LCC package optical module to be desoldered is h1, and h1 > h2, 0.2 mm < h2 < 0.3 mm. Designing a smaller distance between the inner wall surface of the desoldering part and the solder on the exposed solder joints can not only ensure sufficient contact between the thermally conductive adhesive and the desoldering part and the solder, but also effectively avoid the waste of the thermally conductive adhesive caused by too large a gap. At the same time, designing the entire desoldering part on the pads can prevent the solder mask outside the pads of the PCB from being damaged at high temperature during the heating process. Designing a larger distance between the inner wall of the heating part and the outer peripheral wall of the LCC package optical module can effectively prevent the LCC package optical module from being damaged during the heating process.

[0030] Further, in step S2, the thermally conductive adhesive is a semi-solid silicone thermally conductive adhesive.

[0031] Further, in step S4, use an external lifting device to place the three temperature-controlled soldering irons into the 3 heating holes simultaneously and respectively.

[0032] Compared with the prior art, the beneficial effects of a non-destructive desoldering method for an LCC package optical module provided by the present invention are as follows:

[0033] 1. The present invention uses a deformable thermally conductive material as a heat bridge, enabling the solder joints around the LCC package optical module to be desoldered simultaneously, with a fast desoldering speed, safety and reliability, improving the desoldering quality and avoiding solder joint bridging.

[0034] 2. The present invention fills a thermally conductive adhesive between the desoldering tooling and the exposed solder joints. Due to the good ductility and plasticity of the thermally conductive adhesive, it reduces the dependence on the dimensional accuracy of the desoldering tooling, enables the solder joints around the device to be heated simultaneously, and avoids the problems of damaging the components and the PCB board due to too long contact time or multiple heating caused by the hard contact desoldering method.

[0035] 3. The present invention designs a special desoldering tooling. The tooling is made of copper material, has good thermal conductivity, is easy to process and has a low cost; the tooling is designed for three-point centroid heating to ensure the thermal conduction efficiency and uniformity, and conventional temperature-controlled soldering irons of various shapes can be used for heating, with universality.

[0036] 4. The funnel-shaped design of the heating frame of the present invention can not only ensure sufficient contact between the desoldering part and the thermally conductive adhesive, but also protect the LCC package optical module from the high temperature of the heating frame. Description of the Drawings

[0037] Figure 1It is a schematic structural diagram of an LCC packaged optical module in the prior art;

[0038] Figure 2 It is a schematic overall structural diagram when the desoldering tooling used in the embodiment of the non-destructive desoldering method of an LCC packaged optical module of the present invention is in use;

[0039] Figure 3 It is a top view of the structure of the desoldering tooling used in the embodiment of the non-destructive desoldering method of an LCC packaged optical module of the present invention;

[0040] Figure 4 is Figure 3 the cross-sectional view of;

[0041] Figure 5 It is a process flow chart of the non-destructive desoldering method of an LCC packaged optical module of the present invention.

[0042] Reference numerals in the attached drawings:

[0043] 1. Heating frame; 2. Boss; 3. Heating hole; 4. Heating part; 5. Desoldering part; 6. Temperature-controlled soldering iron; 7. Lifting device; A. Cover plate; B. Bracket; C. PCB board; D. Optical fiber. Detailed implementation manners

[0044] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] In order to solve the technical problems in the prior art, such as high requirements for the dimensional accuracy of the desoldering device, many restrictions on the desoldering time, and great influence on the inconsistency of solder joints, resulting in difficult desoldering and over-reliance on the skill level of operators, a non-destructive desoldering method for an LCC packaged optical module is provided. The basic implementation idea of this method is:

[0046] S1, use a non-woven fabric dipped in anhydrous ethanol to clean other attachments on the exposed solder joints of the LCC packaged optical module device, so that the solder of the exposed solder joints is fully exposed to the air, and use CM8C high-temperature tape to protect the non-desoldering parts on the circuit board. Among them, two layers of heat insulation protection are carried out on the component side of the circuit board, and one layer of heat insulation protection is carried out on the welding side of the circuit board to reduce the influence on the non-desoldering parts of the circuit board and prevent the solder joints of components from melting, collapsing or bridging due to overheating of the non-desoldering parts.

[0047] S2. Apply the shaped thermal conductive putty on the solder joints around the LCC packaged optical module device. Use an anti-static flat-tip tweezer to gently press the thermal conductive putty to make it closely adhere to the solder joints of the LCC packaged optical module device. The thermal conductive putty should be coated as evenly as possible to ensure uniform heat conduction.

[0048] S3. Hold the desoldering tooling and make the gaps between it and the LCC packaged optical module device uniform and aligned in all directions (up, down, left, and right). Place the desoldering tooling on the thermal conductive putty coated on the LCC packaged optical module device.

[0049] S4. Set the temperature of the temperature-controlled soldering iron 6 to 305°C - 320°C. Use the external lifting device 7 to place 3 temperature-controlled soldering irons 6 into 3 heating holes simultaneously, and melt an appropriate amount of solder in the heating hole 3 of the desoldering tooling and continue heating. After heating for 10 - 20 s until the solder joints are melted, remove the temperature-controlled soldering iron 6. Use the anti-static tweezer to pick up the LCC packaged optical module device and the desoldering tooling in sequence and place them on the heat insulation pad for heat dissipation.

[0050] S5. Use a non-woven fabric dipped in anhydrous ethanol to wipe the thermal conductive putty on the circuit board and clean the solder pads on the PCB board. This method can be used repeatedly to ensure that the solder pads are intact and the PCB board is clean. Use a non-woven fabric dipped in anhydrous ethanol to clean the thermal conductive putty adhered to the LCC packaged optical module device to ensure that the appearance and solder pads of the LCC packaged optical module device are clean without any excess.

[0051] The proposal of the above method has the following advantages: First, using a malleable thermal conductive material as the heat bridge enables the simultaneous desoldering of the solder joints around the LCC packaged optical module, with a fast desoldering speed, safety, and reliability, improving the desoldering quality and avoiding solder joint bridging. Second, filling the thermal conductive putty between the desoldering tooling and the exposed solder joints reduces the dependence on the dimensional accuracy of the desoldering tooling due to the good ductility and plasticity of the thermal conductive putty, enabling the simultaneous heating of the solder joints around the device and avoiding the problems of overlong contact time or multiple heating caused by the hard contact desoldering method, which may damage the components and the PCB board. Third, the thermal conductive putty forms a wrap around the solder, heating the solder more thoroughly, improving the heating efficiency, and shortening the heating time. Fourth, when the temperature-controlled soldering iron 6 heats and melts the solder in the heating hole, heat transfer to the heating frame is achieved through the melted solder. Compared with directly heating the heating frame by the temperature-controlled soldering iron 6, the heat conduction is more efficient.

[0052] To introduce the present invention in more detail, a surface mount device using LCC48 packaging with a structure size of 16.4 mm × 16.4 mm × 4 mm and the process of its non-destructive desoldering is taken as a specific embodiment. This embodiment provides a device for implementing the above method. The device is as Figure 2-5 shown. The desoldering tooling is designed in an open "mouth" shape according to the device shape and solder terminals. The overall size of the tooling is small, which can minimize the interference with non-desoldering parts. The tooling design is as Figure 1as shown

[0053] The desoldering tooling includes a heating frame 1, a boss 2, and a heating hole 3;

[0054] The boss 2 is located on the outer peripheral wall of the heating frame 1 and protrudes from the outer peripheral wall of the heating frame 1;

[0055] The heating hole 3 is arranged at the top of the boss 2 and is formed by being recessed downward.

[0056] Among them, the heating frame 1 includes a heating part 4 at the top and a desoldering part 5 at the bottom.

[0057] The heating part adopts the three-point centroid heating method, dividing the total mass of the tooling into three parts, with a heating hole 3 set at the centroid of each part, a total of three heating holes 3, to achieve three-point rapid heat conduction. The heating hole 3 is designed as a blind hole, and the hole diameter is designed as Φ4 - Φ5mm according to the tip size of a conventional temperature-controlled soldering iron.

[0058] The desoldering part is in contact with the PCB board and is designed as a funnel shape with an oblique angle of 60° - 70°, that is, the included angle between the hypotenuse of the desoldering part 5 and the horizontal direction of the bottom edge. According to the package size of the LCC package optical module device, the inner size of the desoldering tooling is determined. The inner size of the desoldering part 5 is about 0.2 - 0.3mm larger than the package size of the LCC package optical module device, which is convenient for installation and does not cause interference. At the same time, it can control the filling gap of the clay and meet the filling amount of the clay. According to the PCB board package design of the LCC package optical module, the outer size is determined. The outer size of the desoldering part is about 0.1 - 0.2mm smaller than the PCB package design size, that is, the desoldering part is located on the solder pad to minimize the contact between the desoldering tooling and the PCB board outside the solder pad, prevent damage to the solder mask outside the solder pad of the PCB board during the heating process, and avoid damage to the PCB board during heating. The contact heating width between the desoldering part 5 and the PCB board is about 0.7mm - 0.9mm, that is, the wall thickness of the desoldering part is 0.7mm - 0.9mm, meeting the support strength requirements of the desoldering part.

[0059] Thermal conductive putty is a material with high thermal conductivity, usually composed of thermal conductive fillers, resin matrix and other additives. Its main features include: 1. High thermal conductivity: It contains a large amount of fillers with good thermal conductivity such as alumina and boron nitride, which can quickly conduct heat and effectively reduce the temperature of heating elements. 2. Good adhesiveness: It can firmly adhere between the heating element and the heat dissipation component to ensure the stability of heat transfer. 3. Heat resistance: It can maintain stable performance within a certain temperature range and generally can withstand high temperatures from dozens to hundreds of degrees Celsius. 4. Insulation: It has good electrical insulation performance to prevent short circuits between the heating element and the heat dissipation element. Its main application environments include: 1. Electronic devices: It is used between chips such as CPU and GPU and heat sinks to improve heat dissipation efficiency and ensure the stable operation of electronic devices. 2. Industrial field: It can be used for heat dissipation of industrial heating equipment such as motors and transformers to extend the service life of the equipment. 3. New energy field: In solar panels, lithium batteries, etc., it helps with heat dissipation to improve energy conversion efficiency and battery safety.

[0060] It can be seen from this that in the process of using existing technologies, thermal conductive putty usually utilizes its high thermal conductivity to dissipate heat from high-temperature components, such as structures like CPU and heat sinks. The heat of the heating component is dissipated into the air through the thermal conductive putty to achieve the heat dissipation function.

[0061] This invention makes full use of the thermal conductivity, heat resistance, insulation, and strong plasticity of the thermal conductive putty. The thermal conductive putty is filled between the heating frame and the exposed solder joints to reduce the dependence on the dimensional accuracy of the desoldering tooling. Through the plasticity of the thermal conductive putty, the solder is wrapped, and through the thermal conductivity of the thermal conductive putty, the solder wrapped inside is heated. It completely changes the point contact heating or line contact heating methods in the existing technologies and truly realizes the surface contact heating mode, improves the heating efficiency, shortens the heating time, and effectively avoids damage to non-desoldering parts of the LCC package optical module. By using its heat resistance performance, the cleaning efficiency is improved. And because the thermal conductive putty has insulation, during the desoldering process, there will be no phenomenon of device solder joint bridging, avoiding secondary heating to remove tin and clean the solder joints and devices after desoldering, and improving the desoldering quality.

[0062] The specific process of the above device during use is as follows:

[0063] During operation, first knead the thermal conductive putty into a uniform long strip with a diameter of 1 mm to 2 mm for shaping. Subsequently, use tweezers to apply the shaped thermal conductive material to the solder joints around the device to be desoldered (i.e., the LCC package optical module) to achieve heat transfer between the desoldering tooling and the solder joints. During the desoldering process, the melting temperature of the solder is 183°C, while the working temperature of the thermal conductive putty is higher than 200°C, and its heat resistance performance fully meets the requirements of the desoldering operation. In addition, the thermal conductive putty also has good insulation performance, providing guarantee for the safety of the entire desoldering process.

[0064] 1) Clean the exposed solder joints of the LCC package optical module device, making the solder of the solder joints fully exposed to the air. Use CM8C high-temperature tape to cover and paste the non-desoldering parts on the circuit board, with two layers of heat insulation protection on the component side of the circuit board and one layer of heat insulation protection on the soldering side of the circuit board.

[0065] 2) Knead the thermal conductive paste into a uniform strip with a diameter of about 1 mm. The thermal conductive paste is SINWE 3893 thermal conductive paste.

[0066] 3) Apply the shaped thermal conductive paste on the solder joints on the four sides of the LCC package optical module device, and gently press the thermal conductive paste with an anti-static flat-tip tweezer to make it closely and evenly fit with the solder joints of the LCC package optical module device.

[0067] 4) Place the desoldering tooling on the thermal conductive paste coated on the LCC package optical module device, and adjust the gaps between the device and the desoldering tooling in the up-down, left-right directions to be uniform and aligned.

[0068] 5) Set the temperature of the temperature-controlled soldering iron 6 to 310 °C, and use the soldering iron tip of the temperature-controlled soldering iron 6 to melt an appropriate amount of solder in the heating hole of the desoldering tooling and continuously heat.

[0069] 6) After heating for 10 s until the solder joints are melted, use the anti-static tweezer to pick up the LCC package optical module device and the desoldering tooling in sequence and place them on the heat insulation pad for heat dissipation.

[0070] 7) Use a non-woven fabric dipped in anhydrous ethanol to wipe the thermal conductive material on the circuit board, and clean the pads of the LCC package device on the circuit board. This method can be repeated to ensure that the pads of the device are intact and the circuit board is clean and tidy.

[0071] 8) Use a non-woven fabric dipped in anhydrous ethanol to clean the thermal conductive material adhered to the LCC package device to ensure that the appearance and pads of the device are clean and intact.

[0072] The desoldering tooling of the present invention has low structural dimension accuracy, low cost, and the material selection is easy to process. And it can desolder the solder joints around the device simultaneously, enabling the desoldering of the LCC package optical device quickly, safely and reliably, improving the desoldering quality and avoiding solder joint bridging. At the same time, the desoldering process method of the LCC package optical device of the present invention is relatively simple, and on-site operators can operate skillfully and accurately after learning. It can be popularized and applied to the manual desoldering process of FP and QFN devices.

[0073] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for lossless desoldering of an LCC package optical module, characterized in that, The following steps are involved: S1, cleaning the attachments on the exposed solder joints of the LCC package optical module to be desoldered, so that the solder on the exposed solder joints is exposed to the air; S2, applying a circle of thermal conductive adhesive on the cleaned exposed solder joints, so that the thermal conductive adhesive is closely attached to the exposed solder joints; S3, after the thermal conductive glue is applied, a desoldering tool is obtained, the desoldering tool comprising a heating frame (1), a heating hole (3) located on the periphery of the heating frame (1), and a temperature-controlled soldering iron (6) whose size matches that of the heating hole (3), the shape of the heating frame (1) matches the shape of the LCC packaged optical module to be desoldered, and the heating frame (1) can be placed on the periphery of the thermal conductive glue, so that the inner wall of the heating frame (1) is tightly fitted with the thermal conductive glue; S4, installing a desoldering tool, placing a heating frame (1) on the periphery of the thermal conductive paste, and after the desoldering tool is installed, placing the temperature-controlled soldering iron (6) in the heating hole (3); S5, wait for the temperature-controlled soldering iron (6) to rise to a set temperature, add solder, and heat it to a molten state, and continue to heat the heating frame (1) with the molten solder for a set time, so that the solder of the exposed solder joint is in a molten state; S6, transfer the temperature-controlled soldering iron (6) to separate it from the heating hole (3), use tweezers to clamp the LCC packaged optical module and the desoldering tool in sequence and remove them, and finally clean the thermal conductive glue to complete the desoldering of the LCC packaged optical module.

2. The non-destructive desoldering method of the LCC packaged optical module according to claim 1, characterized in that: In step S3, one side of the heating frame (1) has an opening to allow the optical fiber of the LCC packaged optical module to be desoldered to pass through; The outer peripheral wall of the heating frame (1) is provided with at least two bosses (2), and the top of each boss (2) is provided with a heating hole (3).

3. The non-destructive desoldering method of the LCC packaged optical module according to claim 2, characterized in that: In step S3, the heating frame (1) is divided into at least two parts along the circumferential direction according to mass, wherein each part has a centroid, and the boss (2) is arranged at the centroid.

4. The non-destructive desoldering method of the LCC packaged optical module according to claim 3, characterized in that: In step S3, the heating frame (1) is divided into three parts along the circumferential direction according to mass.

5. The non-destructive desoldering method of the LCC packaged optical module according to claim 2, characterized in that: In step S3, the heating frame (1) is made of copper.

6. The non-destructive desoldering method of the LCC packaged optical module according to claim 2, characterized in that: In step S3, the upper part of the heating frame (1) is in the shape of a square straight cylinder, and the lower part is in the shape of a square conical cylinder. The large end of the square conical cylinder is connected to the lower end of the square straight cylinder. The square straight cylinder and the square conical cylinder respectively constitute the heating part (4) and the desoldering part (5) of the heating frame (1); the boss (2) is arranged on the outer peripheral wall of the square straight cylinder.

7. The non-destructive desoldering method of the LCC packaged optical module according to claim 6, characterized in that: In step S4, when installing the desoldering and soldering tooling, place the square conical tube of the heating frame (1) on the pads of the PCB of the LCC package optical module to be desoldered, and make the minimum distance between its inner wall surface and the solder on the exposed solder joints be h2. The minimum distance between the inner wall of the square straight tube and the outer peripheral wall of the LCC package optical module to be desoldered is h1, and h1 > h2, 0.2mm < h2 < 0.3mm.

8. The non-destructive desoldering method for the LCC package optical module according to claim 1, characterized in that: In step S2, the thermal conductive adhesive is a semi-solid silicone thermal conductive adhesive.

9. The non-destructive desoldering method for the LCC package optical module according to claim 4, characterized in that: In step S4, use an external lifting device (7) to place the three temperature-controlled soldering irons (6) into the 3 heating holes (3) simultaneously and respectively.

Images