Dynamic wave gold removal process method for lead component

Abstract

The invention belongs to the field of electronic assembly, and provides a lead component dynamic wave gold removal process method, which comprises the complete method flow of pretreatment, tin material heating, lead component insertion, soldering flux spraying, preheating, dynamic wave gold removal treatment, process monitoring and parameter adjustment, and post-treatment. According to the process method, the dynamic waves can be applied to the gold removing process of the lead component, gold removing treatment of the lead component can be completed only at a time, the gold removing time can be shortened by more than 50%, and the production efficiency is greatly improved. Due to the strong permeation and stirring capacity of the dynamic waves, local gold element aggregation is avoided, the internal solubility and temperature of the whole tin material are more uniform, gold removal of a lead component is more thorough, the gold element content of the surface of a lead leg after gold removal is only 0.5-0.6 Wt%, the gold removal treatment degrees of all parts are uniform and consistent, and the one-time gold removal qualification rate can reach 99.6%. According to the invention, the gold removing efficiency and quality of the lead component are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of gold removal technology for electronic components during assembly. Specifically, it relates to a dynamic wave gold removal process for leaded components. Background Technology

[0002] With the advancement of domestic production of leaded components, there are more and more metal-ceramic packaged leaded components. The leads of these leaded components are generally gold-plated to improve corrosion resistance during storage. However, during the electrical assembly soldering process, gold diffuses into the solder to form a brittle intermetallic compound AuSn4. When the mass ratio of gold at the solder interface exceeds 3%, there is a risk of "gold brittleness", which seriously affects the long-term reliability of electronic products. According to the requirements of relevant standards in the electronic assembly industry, in order to prevent the risk of "gold brittleness", the leaded components need to be gold-removed before board-level assembly to remove the gold plating on the leads.

[0003] The traditional method for removing gold from leaded components is the "double-plating" process, which includes the double-plating method, reflow method, and soldering iron method, with the double-plating method being the most common. The double-plating method involves immersing the part to be gold-removed in the gold-removing plating pot for 2 seconds, allowing it to cool, and then repeating the process with the soldering plating pot, ensuring that 95% of the solderable portion has been gold-removed. While the double-plating method offers high flexibility, it also has significant drawbacks. Currently, component lead pitches are often quite narrow, with lead center distances below 0.8mm being very common. During the gold removal process, the molten solder surface exhibits surface tension, which is essentially due to intermolecular forces. Molten solder on two adjacent leads attracts each other under the influence of these intermolecular forces, leading to solder bridging. Furthermore, the double-plating process is entirely manual, resulting in low efficiency and an inability to guarantee consistent solder layer quality, negatively impacting surface mount soldering performance. Summary of the Invention

[0004] The purpose of this invention is to provide a dynamic wave gold removal process for leaded components, using dynamic solder material for gold removal, and employing dynamic wave design and mechanism to improve the efficiency and quality of gold removal for leaded components.

[0005] This invention provides a dynamic wave gold removal process for leaded components, comprising: S1. Heating the solder; S2. Pre-treat, insert, apply flux, and preheat the lead components; S3. Drive the solder flow to perform dynamic wave gold removal on the lead components in the form of dynamic wave solder; the gold removal process lasts for no more than 3 seconds.

[0006] Optionally, the solder material can be Sn63Pb37 or Sn60Pb40, and the heating temperature of the solder material is 260℃~285℃. Optionally, before driving the solder flow, the method further includes: The gold content in the heated tin is tested, and the tin is replaced when the gold weight percentage is greater than 0.2 Wt%.

[0007] Optionally, an infrared or hot air heating system can be used to preheat the lead terminals after the flux is sprayed. The preheating power and time of the infrared heating system are set to 10% first, 10s-30s, and then 80%-90%, 30s-50s.

[0008] Optionally, the preheating temperature of the hot air heating system is 130℃~150℃.

[0009] Optionally, if wire bonding is used during the gold removal process of the lead components, the bonding moving speed is 2mm / s to 12mm / s.

[0010] Optionally, the solder flow can be driven by at least one of the following methods: Ultrasonic vibration, mechanical vibration, and gas injection.

[0011] Optionally, the method further includes: Real-time monitoring of the gold removal effect on leaded components; adjustment of the peak height of the dynamic wave of solder flow or soldering time based on visual inspection results.

[0012] The beneficial effects of this invention are: 1. High efficiency and speed: By using dynamic waves in the gold removal process of lead components, this invention enables lead components to complete the gold removal process in one go, reducing the gold removal time by more than 50% and significantly improving production efficiency.

[0013] 2. Thorough and uniform gold removal: The powerful penetration and stirring ability of the dynamic wave avoids the local accumulation of gold elements, making the solubility and temperature of the entire tin material more uniform, and making the gold removal of lead components more thorough. After gold removal, the gold element content on the lead surface is only 0.5~0.6Wt%, and the degree of gold removal treatment in each part is uniform and consistent, with a first-time gold removal pass rate of up to 99.6%. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1This is a schematic flowchart of the dynamic wave gold removal process for leaded components of the present invention. Figure 2 This is a schematic diagram of a typical implementation of a dynamic wave gold removal processing device; Figure 3 The comparison shows SEM images and gold removal effects after processing the surface of front lead components and using the traditional "double tinning" gold removal process versus the dynamic wave gold removal process of this invention. Explanation of reference numerals in the attached figures: 1. Lead wire components; 2. Tooling; 3. Solder nozzle; 4. Solder bath; 5. Solder; 6. Dynamic wave generator. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0017] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0018] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0020] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0022] The objective of this invention can be achieved through the following technical solutions: This invention provides a dynamic wave gold removal process for leaded components, comprising the following steps: 1. Pre-treatment: Check and confirm the anti-static measures of the working environment, and perform pre-treatment such as unpacking and visual inspection of the leaded components to be treated.

[0023] 2. Heating the solder: Place one of the solid solders of Sn63Pb37 or Sn60Pb40 specifications in a solder pot and heat it to 260℃~285℃ to melt the solder into liquid solder.

[0024] 3. Lead component insertion: Insert the pre-treated lead components into a dedicated dynamic wave gold removal fixture, so that the lead terminals of the lead components to be gold removed protrude from the surface of the fixture.

[0025] 4. Apply flux: Use an automatic spraying mechanism to apply flux to the area to be gold-removed, so that the surface of the lead terminals of the lead components to be gold-removed is fully in contact with the flux.

[0026] 5. Preheating: Use an infrared or hot air heating system to preheat the lead terminals after applying flux. The preheating power and time of the infrared heating system are set to 10% first, 10s-30s, then 80%-90%, 30s-50s. The preheating temperature of the hot air heating system is 130℃-150℃.

[0027] 6. Dynamic Wave Gold Removal Process: A specific type of dynamic wave is applied to the solder, and the preheated leaded components to be gold-removed are immersed in the molten solder for gold removal. The gold removal time of the leaded components is controlled by a program to not exceed 3 seconds. If wire bonding is used, the moving speed is set to 2mm / s to 12mm / s; if spot bonding is used, the gold removal time does not exceed 3 seconds. The dynamic wave can be driven by one or more of ultrasonic vibration, mechanical vibration, and gas injection to form a specific shape of dynamic wave solder. The purpose of dynamic wave action is: 1) Enhanced dissolution: It enables the solder to flow rapidly on the surface of the lead terminals of leaded components, avoiding local gold element accumulation and significantly improving the gold removal effect; 2) Promoted reaction: The micro-stirring and local high temperature and high pressure effect generated by the dynamic wave can accelerate the alloy reaction process, activate the gold surface, and significantly improve the alloy reaction rate between the solder and gold elements; 3) Prevented solder adhesion: The continuous physical disturbance can effectively reduce the surface tension of the solder and prevent the solder from adhering to each other between adjacent leads; 4) Uniform treatment: It makes the solubility and temperature of the entire solder more uniform, ensuring that the degree of gold removal treatment is consistent in all parts of the leaded components.

[0028] 7. Process monitoring and parameter adjustment: 1) The gold content in the solder is tested monthly. When the gold content by weight is greater than 0.2 Wt%, the solder is replaced; 2) The gold removal effect of the lead components is tested in real time. The peak height of the dynamic wave or the soldering time is adjusted according to the visual inspection results to ensure that 95% of the area of ​​the lead terminal is gold removed; 3) The dedicated dynamic wave gold removal fixture is cleaned and dried with water every day to prevent contamination of the lead components.

[0029] 8. Post-processing: Remove the gold-removed leaded components from the tooling and place them on a dedicated tray for board-level assembly or storage.

[0030] The designed method and process can improve the efficiency and quality of gold removal from leaded components. Specifically, it employs dynamic solder for gold removal, where a flowing solder reacts with the gold plating on the lead wires to rapidly remove the gold. This effectively controls the gold removal location, time, and residual solder amount, and eliminates the need for post-removal cleaning, significantly improving the gold removal effect. Furthermore, when the lead spacing is narrow, the dynamic wave effectively reduces the surface tension of the solder, preventing solder on adjacent leads from attracting each other and causing solder bridging. This process further enhances the efficiency and quality of gold removal from leaded components.

[0031] like Figure 1 A dynamic wave gold removal process for leaded components includes eight steps, and a specific embodiment is as follows: 1. Pre-treatment: Check and confirm the anti-static measures of the working environment. Take a batch of CSOP-08 packaged leaded components and check that the components are free from contamination and the pins are free from deformation. Select a gold removal tool with a slot width of 2mm, a hole diameter of 0.6mm, and a hole spacing of 1.26mm according to the package size.

[0032] 2. Heating the solder: Using the solder pot of the selective wave soldering equipment as the solder bath, place the strip of Sn60Pb40 solder in the solder bath, and set the heating temperature to 265℃ to melt the strip of solder into liquid solder.

[0033] 3. Lead wire component insertion: such as Figure 2 The pre-treated lead component 1 is vertically inserted from above into the corresponding hole of the dynamic wave gold removal fixture 2, so that the lead terminal of the lead component to be gold removed extends out of the lower surface of the fixture 2.

[0034] 4. Applying flux: Place the lead components and tools on the equipment track, and use the automatic flux spraying mechanism of the selective wave soldering equipment to apply flux. The spraying area is controlled by the equipment programming to cover all areas to be gold removed. The spraying method is wire spraying at a speed of 5mm / s to 10mm / s, so that the surface of the lead terminals of the lead components to be gold removed is fully in contact with the flux.

[0035] 5. Preheating: The lead terminals after flux spraying are preheated using the infrared and hot air heating systems of the selective wave soldering equipment. The bottom uses an infrared heating system with a preheating start temperature of 150°C, and the power and duration are set to 10% and 30s first, then 80% to 90% and 40s. The top uses a hot air heating system with a temperature of 150°C.

[0036] 6. Dynamic wave gold removal process: such as Figure 2 The dynamic wave generator 6 of the selective wave soldering equipment generates dynamic waves by injecting nitrogen gas. The preheated lead components and the working device are transported to the equipment soldering area via the equipment track. The movement of the solder bath 4 is controlled by the equipment programming. The solder nozzle 3 is fixed to the solder bath 4 by a mechanical structure and moves under the control of the program to perform dynamic wave gold removal below the pin of the lead component 1. The program adopts the wire soldering method and the speed is set to 5mm / s to ensure that the gold removal time of the lead terminal does not exceed 3s.

[0037] 7. Gold removal treatment of other direction pins: Take the gold-removed lead component 1 out of the fixture 2 and rotate it 180°. Perform gold removal treatment on the other side of the unremoved pins according to steps 3 to 6.

[0038] 8. Packaging and Warehousing: Remove the gold-removed lead components 1 from tooling 2 and place them on a special pallet for board-level assembly or warehousing.

[0039] Figure 3 This is a comparison of SEM images and gold removal effects of the surface of leaded components before processing and after using the traditional "double tinning" gold removal process and the dynamic wave gold removal process of this invention. This invention uses the design and mechanism of dynamic waves to improve the efficiency and quality of gold removal from leaded components.

[0040] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A dynamic wave gold removal process for leaded components, characterized in that, include: S1. Heating the solder; S2. Pre-treat, insert, apply flux, and preheat the lead components; S3. Drive the solder flow to perform dynamic wave gold removal on the lead components in the form of dynamic wave solder; the gold removal process lasts for no more than 3 seconds.

2. The dynamic wave gold removal process for leaded components according to claim 1, characterized in that, The tin material used is Sn63Pb37 or Sn60Pb40, and the heating temperature of the tin material is 260℃~285℃.

3. The dynamic wave gold removal process for leaded components according to claim 1, characterized in that, Before driving the flow of solder, the method further includes: The gold content in the heated tin is tested, and the tin is replaced when the gold weight percentage is greater than 0.2 Wt%.

4. The dynamic wave gold removal process for leaded components according to claim 1, characterized in that, The lead terminals after flux spraying are preheated using an infrared or hot air heating system. The preheating power and duration of the infrared heating system are set to 10% first, 10s-30s, then 80%-90%, 30s-50s.

5. The dynamic wave gold removal process for leaded components according to claim 1, characterized in that, The preheating temperature of the hot air heating system is 130℃~150℃.

6. The dynamic wave gold removal process for leaded components according to claim 1, characterized in that, If wire bonding is used during the gold removal process of leaded components, the bonding moving speed is 2mm / s to 12mm / s.

7. The dynamic wave gold removal process for leaded components according to claim 1, characterized in that, The solder flow is driven by at least one of the following methods to generate a smooth and rapid dynamic wave: Ultrasonic vibration, mechanical vibration, and gas injection.

8. The dynamic wave gold removal process for leaded components according to claim 1, characterized in that, The method further includes: Real-time monitoring of the gold removal effect on leaded components; adjustment of the flow speed of the dynamic wave of solder flow and the soldering movement speed based on visual inspection results.

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