Method and equipment for treating residual soldering flux of soldering paste sintering process product

Abstract

The invention discloses a soldering paste sintering process product soldering flux residue treatment method and equipment thereof. The method comprises the steps that a product obtained after soldering paste sintering is immersed in a mixed solution of a water-based cleaning agent and deionized water at the temperature of 50-70 DEG C for high-frequency ultrasonic cleaning; then ultrasonic rinsing is conducted twice, and residual liquid on the surface of the product is blown away through high-pressure airflow in a closed environment after rinsing; and finally, hot air convection or vacuum auxiliary drying is adopted. Through the steps of cleaning, rinsing, wind cutting, drying and the like, product scaling powder residues are effectively removed, and efficient production is achieved.

Description

Technical Field

[0001] The present invention relates to a method for treating flux residue of a solder paste sintering process product and an automatic cleaning device therefor. Background Art

[0002] In the process of chip bonding using the solder paste sintering process, solder paste is used as a welding material to achieve a reliable connection between the chip and the lead frame. Solder paste is a paste-like mixture composed of welding metal particles and flux. The flux mainly has two functions in the solder paste. One is to remove metal oxides and other substances that make the metal material lose surface activity during the welding process; the other is to act as a carrier for the solder, controlling and supporting the forming and flowing of the solder. During the entire welding process, as the temperature rises, the flux will play the role of removing metal oxides and preventing further oxidation of the base metal material. However, under the action of high temperature, part of the flux will volatilize as the temperature rises, and part of the non-volatile substances will remain in the solder and on the surface of the solder, and firmly adhere to the surface of the solder as the temperature cools. Flux residue may affect the stability and reliability of the product, increasing the resistance and thermal resistance of the welding, thereby causing product failure. For example, a method for flux cleaning disclosed in CN118831870A first uses the pure water cleaning method to perform the first pure water cleaning on the substrate product; then selects a chemical cleaning solution and pure water in a preset ratio according to the type of flux and performs ultrasonic cleaning on the substrate product; finally, uses the pure water cleaning method again to perform the second pure water cleaning on the substrate product after ultrasonic cleaning; only water is used to clean the product before and after, and this step can only clean the impurities slightly attached to the surface of the product. Although a chemical cleaning solution is also used, the cleaning temperature is not set, and the best cleaning effect of the cleaning solution cannot be exerted. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a method for treating flux residue of a solder paste sintering process product and an apparatus therefor.

[0004] The present invention is achieved through the following technical solutions.

[0005] A method for treating flux residue of a solder paste sintering process product provided by the present invention includes the following steps:

[0006] (1) Cleaning: Immerse the product after solder paste sintering in a mixed solution of a water-based cleaning agent and deionized water at a temperature of 50 - 70 °C, and vibrate with high-frequency ultrasonic waves of 20 - 60 kHz for 10 - 15 minutes;

[0007] (2) Rinsing: In the first step, rinse with deionized water at 30 - 40 °C for 5 - 10 minutes, and in the second step, rinse with deionized water at 30 - 40 °C for 2 - 5 minutes. During the rinsing process, apply ultrasonic vibration of 20 - 60 kHz synchronously;

[0008] (3) Air shear: Use high-pressure air flow to blow off the residual liquid on the product surface in a closed environment;

[0009] (4) Drying: Adopt hot air convection or vacuum-assisted drying, the drying temperature is 50 - 100 °C, and the time is 10 - 30 minutes.

[0010] In the step (1), the water-based cleaning agent contains surfactants and chelating agents, and the volume ratio thereof to deionized water is 1:3 to 1:5.

[0011] In the step (1), the ultrasonic vibration adopts multi-frequency collaborative alternating vibration of 25 kHz low-frequency ultrasonic wave and 40 kHz high-frequency ultrasonic wave.

[0012] In the step (2), the rinsing process adopts a countercurrent rinsing system, the rinsing water flow rate is 0.3 - 0.5 m / s, and a conductivity sensor is configured to monitor the water quality in real time, and the deionized water is replaced when the conductivity exceeds 5 μS / cm.

[0013] In the step (4), the drying process dynamically adjusts the temperature through an infrared sensor, and introduces a vacuum negative pressure environment to accelerate the evaporation of moisture.

[0014] The cleaning uses a closed-loop cleaning system, and the closed-loop cleaning system integrates a reverse osmosis membrane and an ion exchange device for recovering the cleaning wastewater and recycling it.

[0015] It also includes an on-line quality monitoring module, which determines the residue removal rate in real time through high-resolution visual inspection and infrared spectroscopy analysis.

[0016] The method is adapted to the treatment of flux residues of DFN, QFN, BGA packages and MEMS devices.

[0017] An automatic cleaning device, comprising:

[0018] An ultrasonic cleaning tank, configured with a multi-frequency ultrasonic generator and a turbulent flow device;

[0019] A countercurrent rinsing tank, equipped with a conductivity sensor and a dynamic water change module;

[0020] A vacuum drying oven, integrated with an infrared temperature control and humidity feedback system;

[0021] A central controller, connecting each module through the Internet of Things (IoT) and optimizing the process parameters in real time.

[0022] The beneficial effect of the present invention is that through steps such as cleaning, rinsing, air shear, and drying, the effective removal of flux residues on the product and high-efficiency production are realized. Description of the Drawings

[0023] Figure 1Schematic diagram of the process of the present invention;

[0024] Figure 2 Front and back appearance views of the product of the present invention before and after cleaning;

[0025] Figure 3 Ultrasonic scan views of the product of the present invention before and after cleaning. Detailed implementation manners

[0026] The technical solution of the present invention will be further described below, but the scope of protection claimed is not limited thereto.

[0027] After the solder paste sintering process product is treated with flux cleaning, the flux residues remaining in the die bonding and sintering processes are effectively removed, the surface activity of the copper substrate is improved, the reliability of the product in the encapsulation process is enhanced, the delamination between the molding compound and the frame is reduced, the production efficiency is high, and it is suitable for mass production of products.

[0028] A method for treating flux residues of a solder paste sintering process product includes the following steps:

[0029] (1) Cleaning: Immerse the product after solder paste sintering in a mixed solution of a water-based cleaning agent and deionized water at a temperature of 50 - 70 °C, and vibrate with 20 - 60 kHz high-frequency ultrasonic waves for 10 - 15 minutes;

[0030] (2) Rinsing: In the first step, rinse with deionized water at 30 - 40 °C for 5 - 10 minutes, and in the second step, rinse with deionized water at 30 - 40 °C for 2 - 5 minutes. Apply 20 - 60 kHz ultrasonic vibration synchronously during the rinsing process;

[0031] (3) Air knife: Use high-pressure air flow to blow off the residual liquid on the product surface in a closed environment;

[0032] (4) Drying: Adopt hot air convection or vacuum-assisted drying, with a drying temperature of 50 - 100 °C and a time of 10 - 30 minutes.

[0033] In the step (1), the water-based cleaning agent contains a surfactant and a chelating agent, and its volume ratio with deionized water is 1:3 to 1:5.

[0034] In the step (1), the ultrasonic vibration adopts multi-frequency collaborative and alternating vibration of 25 kHz low-frequency ultrasonic waves and 40 kHz high-frequency ultrasonic waves.

[0035] In the step (2), the rinsing process adopts a countercurrent rinsing system, the rinsing water flow rate is 0.3 - 0.5 m / s, and a conductivity sensor is configured to monitor the water quality in real time. When the conductivity exceeds 5 μS / cm, replace the deionized water.

[0036] In step (4), the drying process dynamically adjusts the temperature through an infrared sensor and introduces a vacuum negative pressure environment to accelerate water evaporation.

[0037] Closed-loop cleaning system is used for cleaning, which integrates a reverse osmosis membrane and an ion exchange device to recover and recycle the cleaning wastewater.

[0038] An on-line quality monitoring module is also included to determine the residue removal rate in real time through high-resolution vision detection and infrared spectroscopy analysis.

[0039] The method is applicable to the treatment of flux residues in DFN, QFN, BGA packages and MEMS devices.

[0040] An automatic cleaning device includes:

[0041] An ultrasonic cleaning tank equipped with a multi-frequency ultrasonic generator and a turbulence device;

[0042] A countercurrent rinsing tank equipped with a conductivity sensor and a dynamic water change module;

[0043] A vacuum drying oven integrated with an infrared temperature control and humidity feedback system;

[0044] A central controller connects each module through the Internet of Things (IoT) and optimizes the process parameters in real time.

[0045] In the cleaning step of the present invention, a water-based cleaning agent is used as the cleaning medium. By mixing it with deionized water and circulating heating, the cleaning solution is kept at a constant temperature of 60 °C to improve the activity between the cleaning agent molecules, accelerate the softening and saponification reactions of the flux residues, weaken the adhesion of the flux, and use 40 kHz high-frequency ultrasonic waves to vibrate the cleaning agent so that the flux residues fall off and dissolve from the solder surface. During this process, the cleaning effect is controlled by the concentration of the cleaning agent, the temperature of the cleaning agent, and the cleaning time.

[0046] In the rinsing step, deionized water is used as the rinsing medium, and a two-step rinsing method is used to effectively remove the cleaning agent and flux residues. During the rinsing process, the deionized water is heated to 30 °C by a heating device to maintain the constant temperature state of the rinsing solution, thereby controlling the stability of the process, weakening the influence of the environment on the cleaning process. The cleaning agent and flux residues are removed from the product surface and into the rinsing medium through the vibration of 40 kHz high-frequency ultrasonic waves, and larger particles are removed through a filtering device. The cleaning effect of the cleaning agent and flux residues is controlled by the temperature and rinsing time of the rinsing medium in two rinsing tanks.

[0047] In the air-knife step, a hair dryer is used in a closed box to remove larger deionized water droplets on the product surface, thereby improving the product drying efficiency.

[0048] In the drying step, the inside of the oven is heated by means of hot air convection, and water vapor is removed by a suction device, so as to dry the product, reduce the influence of moisture on the plastic-encapsulated product, and control the removal effect of the product's water vapor by the heating temperature and heating time.

Claims

1. A method for treating flux residue in a solder paste sintering process product, characterized in that It includes the following steps: (1) Cleaning: Immerse the product after solder paste sintering into a mixed solution of water-based cleaning agent and deionized water at a temperature of 50 - 70 °C, and perform high-frequency ultrasonic vibration at 20 - 60 kHz for 10 - 15 minutes; (2) Rinsing: In the first step, rinse with deionized water at 30 - 40 °C for 5 - 10 minutes, and in the second step, rinse with deionized water at 30 - 40 °C for 2 - 5 minutes. Apply 20 - 60 kHz ultrasonic vibration synchronously during the rinsing process; (3) Air knife: Use high-pressure air flow to blow off the residual liquid on the product surface in a closed environment; (4) Drying: Adopt hot air convection or vacuum-assisted drying. The drying temperature is 50 - 100 °C, and the time is 10 - 30 minutes.

2. The method for treating flux residue according to claim 1, wherein: In the step (1), the water-based cleaning agent contains surfactants and chelating agents, and its volume ratio with deionized water is 1:3 to 1:

5.

3. The method for treating flux residue according to claim 1, wherein: In the step (1), the ultrasonic vibration adopts multi-frequency collaborative alternating vibration of 25 kHz low-frequency ultrasonic wave and 40 kHz high-frequency ultrasonic wave.

4. The flux residue treatment method according to claim 1, characterized in that: In the step (2), the rinsing process adopts a countercurrent rinsing system. The rinsing water flow rate is 0.3 - 0.5 m / s, and a conductivity sensor is configured to monitor the water quality in real time. When the conductivity exceeds 5 μS / cm, replace the deionized water.

5. The method for treating flux residue according to claim 1, wherein: In the step (4), the temperature is dynamically adjusted by an infrared sensor during the drying process, and a vacuum negative pressure environment is introduced to accelerate water evaporation.

6. The method for treating flux residues according to claim 1, wherein: The cleaning uses a closed-loop cleaning system, and the closed-loop cleaning system integrates a reverse osmosis membrane and an ion exchange device for recycling cleaning wastewater and reusing it.

7. The method for treating flux residue according to claim 1, wherein: It also includes an online quality monitoring module to determine the residue removal rate in real time through high-resolution visual inspection and infrared spectroscopy analysis.

8. The method for treating flux residues according to claim 1, characterized in that: The method is adapted to the flux residue treatment of DFN, QFN, BGA packages and MEMS devices.

9. An automated cleaning device for implementing the method according to any one of claims 1-8, characterized in that, It includes: An ultrasonic cleaning tank configured with a multi-frequency ultrasonic generator and a turbulence device; A countercurrent rinsing tank equipped with a conductivity sensor and a dynamic water change module; A vacuum drying oven integrated with an infrared temperature control and humidity feedback system; A central controller that connects each module through the Internet of Things (IoT) and optimizes the process parameters in real time.

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