A cleaning method of metal indium particles for semiconductor laser package

Abstract

The application relates to a cleaning method for metal indium particles used for semiconductor laser packaging, and is characterized by comprising the following steps: S1, indium particles are soaked and cleaned by using acetone, and then nitrogen blowing is performed; S2, the indium particles cleaned in the step S1 are soaked and cleaned by using a hydrochloric acid-anhydrous ethanol mixed solution, then washed by using anhydrous ethanol, again soaked and cleaned by using anhydrous ethanol, and finally nitrogen blowing is performed; S3, the indium particles cleaned in the step S2 are subjected to plasma cleaning; S4, the indium particles cleaned in the step S3 are subjected to quality inspection to determine whether the indium particles are cleaned qualified or not. The cleaning method for the metal indium particles used for semiconductor laser packaging can effectively remove different types of pollutants on the surface of the indium particles through the step-by-step treatment process of acetone, the hydrochloric acid-anhydrous ethanol mixed solution and plasma cleaning, and the reagent residue on the surface of the cleaned indium particles is reduced by more than 95%.

Description

Technical Field

[0001] This invention relates to a cleaning method for indium granules used in semiconductor laser packaging, belonging to the field of semiconductor laser packaging technology. Background Technology

[0002] Semiconductor lasers, with their advantages of small size, light weight, high electro-optical conversion efficiency, long lifespan, and high reliability, have gradually replaced gas and solid-state lasers in fields such as communications, medical applications, displays, industrial manufacturing, and security, and their application scope is continuously expanding. The waste heat generated by the semiconductor laser chip during operation needs to be effectively and promptly dissipated; otherwise, the laser chip temperature will become too high, reducing the device's luminous efficiency and potentially causing laser failure. Currently, a widely used technical solution is to sinter the semiconductor laser chip onto a heat sink with strong heat dissipation capabilities, effectively dissipating the heat generated during chip operation. For the heat sink and chip to be soldered together, a layer of solder must be deposited on the surface of the heat sink. The commonly used sintering solder is indium. Indium, due to its excellent ductility (plasticity), low vapor pressure, low electrical resistance, high thermal conductivity, strong adhesion, and fatigue resistance, can adhere to various materials, making it widely used in semiconductor laser packaging technology. Indium, as a crucial thermal and electrical conductive connecting material in semiconductor lasers, directly determines the reliability of packaging and the long-term operational stability of devices due to the surface cleanliness. During preparation, storage, and transportation, indium granules are prone to leaving oil, oxide layers, and micron-sized impurity particles on their surface. If indium granules are not cleaned before vapor deposition, these oxide impurities will deposit onto the heat sink surface, increasing the contact resistance between the heat sink and the chip, reducing thermal conductivity, and potentially causing device packaging failure. Existing indium granule cleaning methods generally suffer from incomplete cleaning, reagent residues affecting subsequent packaging processes, and substandard surface gloss and cohesiveness of indium granules, failing to meet the stringent technical requirements for high-reliability packaging of semiconductor lasers. Therefore, there is an urgent need to develop an indium granule cleaning method with standardized processes, stable cleaning effects, and suitability for industrial-scale mass production. Summary of the Invention

[0003] This invention provides a cleaning method for indium particles used in semiconductor laser packaging, which achieves efficient and thorough removal of oil, oxide layer and impurities from the surface of the indium particles, ensuring that the cohesiveness and surface gloss of the indium particles meet the packaging process requirements, thereby improving the packaging reliability and service life of semiconductor lasers.

[0004] A method for cleaning indium granules used in semiconductor laser packaging includes the following steps: S1. The indium particles are soaked and cleaned with acetone, and then dried with nitrogen. S2. The indium particles cleaned in step S1 are soaked and cleaned in a mixture of hydrochloric acid and anhydrous ethanol, then rinsed with anhydrous ethanol, then soaked and cleaned again with anhydrous ethanol, and finally dried with nitrogen. S3. Perform plasma cleaning on the indium particles after cleaning in step S2. S4. Perform a quality inspection on the indium particles after cleaning in step S3 to determine whether the indium particles are qualified for cleaning.

[0005] According to a preferred embodiment of the present invention, in step S1, the mass-to-volume ratio (g / ml) of indium particles to acetone is 1:(1-4).

[0006] According to a preferred embodiment of the present invention, in step S1, the soaking and cleaning time with acetone is 30-50 seconds.

[0007] According to a preferred embodiment of the present invention, in step S2, the mass-volume ratio (g / ml) of indium particles to hydrochloric acid-anhydrous ethanol mixture is 1:(1.25-2).

[0008] According to a preferred embodiment of the present invention, in step S2, the volume ratio of hydrochloric acid to anhydrous ethanol in the hydrochloric acid-anhydrous ethanol mixture is 3:(5-20), wherein the mass concentration of hydrochloric acid is 35%-45%.

[0009] According to a preferred embodiment of the present invention, in step S2, the soaking and cleaning time with the hydrochloric acid-anhydrous ethanol mixture is 5-10 minutes, and the mixture is shaken thoroughly every 1-2 minutes.

[0010] According to a preferred embodiment of the present invention, in step S2, the rinsing is performed 3-5 times with anhydrous ethanol, and the amount of anhydrous ethanol used for each rinse is 250-400 ml.

[0011] According to a preferred embodiment of the present invention, in step S2, the sample is soaked and cleaned with anhydrous ethanol for 3-5 minutes, and the amount of anhydrous ethanol used for soaking and cleaning is 250-400 ml.

[0012] According to a preferred embodiment of the present invention, in step S3, the plasma cleaning time is 5-10 minutes, and the power of the plasma cleaner is 150-200W and the frequency is 13.56 MHz ± 0.1%.

[0013] According to a preferred embodiment of the present invention, in step S4, the standard for qualified indium particle cleaning is as follows: the indium particles are in a completely aggregated state, forming an integral agglomerate, with no dispersed individual indium particles present; the surface of the indium particles has a uniform silvery-white metallic luster, presenting a typical metallic bright appearance.

[0014] According to a preferred embodiment of the present invention, in step S4, if the indium particles are cleaned to the qualified level, the next process is carried out; if the indium particles are not cleaned to the qualified level, they are cleaned again, and if they are still not qualified after cleaning again, they are scrapped.

[0015] Technical features and beneficial effects of the present invention: 1. The cleaning method for indium particles used in semiconductor laser packaging of the present invention, through a step-by-step process of acetone, hydrochloric acid-anhydrous ethanol mixture and plasma cleaning, can effectively remove different types of contaminants on the surface of indium particles compared with the original indium particle cleaning method. The reagent residue on the surface of the indium particles after cleaning is reduced by more than 95%, and the failure rate of the packaged laser is reduced by more than 5%, which greatly improves the quality of the product and reduces the production cost.

[0016] 2. The cleaning method for indium particles used in semiconductor laser packaging of the present invention uses a combination of three anhydrous ethanol rinsing and one immersion process, combined with a strict nitrogen blowing operation, to ensure the cleanliness of the indium particle surface. Plasma cleaning further enhances surface activity, ensuring that the indium particle cohesion and gloss meet the standards, and better adapts to the semiconductor laser packaging process requirements.

[0017] 3. The cleaning method for indium particles used in semiconductor laser packaging of the present invention has a high degree of standardization and is easy to operate. The reagent classification and recycling process is safe and reliable, better meeting environmental protection requirements, and can be directly applied to industrial mass production scenarios. Attached Figure Description

[0018] Figure 1 This is a flowchart of the cleaning method for indium granules used in semiconductor laser packaging according to the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments, but is not limited thereto. The described embodiments are some embodiments of the present invention. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Unless otherwise specified in the embodiments of the present invention, all techniques existing in the art can be used.

[0021] Equipment and material preparation: 1. Equipment: 500ml-1000ml beakers, 100ml-500ml graduated cylinders, 10ml-50ml graduated cylinders, electronic balance with an accuracy of 0.1g, nitrogen gun (outlet pressure: 0.2-0.6MPa), plasma cleaner, plasma cleaning rack, lint-free cloth, acetone recycling bin, waste acid recycling bin, and anhydrous ethanol recycling bin.

[0022] 2. Materials: 5N grade high-purity indium granules, anhydrous ethanol (purity ≥99.8%), hydrochloric acid solution (mass concentration: 35%-45%), acetone (purity ≥99.6%), high vacuum aluminum foil, corrosion-resistant nitrile gloves, and gas masks (protection level KN95 and above).

[0023] The present invention will be further described below with reference to embodiments and accompanying drawings. However, it is not limited thereto.

[0024] Example 1 S1. Place the empty beaker on the electronic balance tray, press the "tare" button to zero the balance, pour 5N grade indium granules vertically into the beaker from the original indium granule packaging bottle along the top of the balance until the balance shows a weight of 75g, remove the beaker and place it stably on the worktable.

[0025] Pour 150ml of acetone into a beaker, start the electronic timer, soak for 40 seconds, then tilt the beaker at 45° and slowly pour the acetone into a dedicated acetone recycling tank. The acetone soaking will dissolve and remove the oil stains on the surface of the indium particles.

[0026] Hold the nitrogen gun and keep the gun tip 15cm away from the surface of the indium particle. Turn on the nitrogen gun to dry the indium particle after it has been soaked and cleaned with acetone until there is no obvious acetone liquid residue on the surface of the indium particle. Then turn off the nitrogen gun.

[0027] S2. Operators should wear corrosion-resistant nitrile gloves and KN95 respirators as required. The preparation should be carried out in a fume hood. Accurately measure 100ml of anhydrous ethanol using a 100ml graduated cylinder and slowly pour it into a dry beaker. Then, measure 30ml of hydrochloric acid solution using a 50ml graduated cylinder and slowly pour it into the anhydrous ethanol along the beaker wall while continuously stirring clockwise with a glass rod at a speed of 60r / min to ensure that the two reagents are mixed evenly. The prepared hydrochloric acid-anhydrous ethanol mixture should be placed in a fume hood for later use.

[0028] After step S1, move the indium granules along with the beaker into a fume hood. Pour the pre-prepared hydrochloric acid-anhydrous ethanol mixture into the beaker, ensuring that the indium granules are completely submerged in the cleaning solution. Start the timer. During the soaking process, gently shake the beaker 4 times every 1 minute by holding the bottom, with each shaking lasting 10 seconds. After soaking for 7 minutes, slowly pour the hydrochloric acid mixture into the waste acid recycling tank.

[0029] Pour 300 ml of anhydrous ethanol into a beaker containing indium granules, hold the beaker and gently shake for 12 seconds to ensure that the indium granules are in full contact with the ethanol. Then pour the ethanol into a dedicated anhydrous ethanol recovery container. Repeat this rinsing operation three times. After the last rinse, pour 300 ml of anhydrous ethanol into the beaker again, soak for 4 minutes, and then pour the ethanol into the recovery container.

[0030] Hold the nitrogen gun again, with the nozzle facing the indium granules in the beaker, maintaining a distance of 15cm. Turn on the nitrogen gun and blow air for 2 minutes. During this time, closely observe the stability of the beaker to avoid it tipping over due to the impact of the airflow.

[0031] S3. Take a clean plasma cleaning rack, apply a small amount of anhydrous ethanol to a lint-free cloth, and wipe the surface of the rack evenly. Place it on a clean workbench to dry. Cut a suitable size of high-vacuum aluminum foil and lay it on the surface of the cleaning rack. Gently wipe the surface of the aluminum foil with a lint-free cloth soaked in anhydrous ethanol. After the ethanol has completely evaporated, slowly pour the indium particles from step S2 onto the plasma cleaning rack. Turn on the power of the plasma cleaner, select the preset program for indium particle cleaning, and set the plasma cleaner to a power of 180 W, a frequency of 13.56 MHz, and a cleaning time of 8 minutes. Place the plasma cleaning rack carrying the indium particles into the plasma cleaning chamber, close the chamber door, start the cleaning program, and after the program has automatically completed, open the chamber door and remove the plasma cleaning rack.

[0032] S4. After cleaning, the indium particles are inspected for quality. The standard for qualified indium particle cleaning is: the indium particles are in a completely aggregated state, forming an integral agglomerate, with no dispersed individual indium particles present; the surface of the indium particles has a uniform silvery-white metallic luster, presenting a typical metallic bright appearance.

[0033] Indium particles that pass the cleaning process will proceed to the next step; indium particles that fail the cleaning process will be cleaned again, and those that still fail the cleaning process will be scrapped.

[0034] Example 2 S1. Place the empty beaker on the electronic balance tray, press the "tare" button to zero the balance, pour 5N grade indium granules vertically from the original packaging bottle into the beaker along the top of the balance until the balance shows a weight of 100g, remove the beaker and place it stably on the worktable.

[0035] Pour 200ml of acetone into a beaker, start the electronic timer, soak for 30 seconds, then tilt the beaker at a 45° angle and slowly pour the acetone into a dedicated acetone recycling tank. The acetone soaking process dissolves and removes the oil stains on the surface of the indium particles.

[0036] Hold the nitrogen gun and keep the gun tip 20cm away from the surface of the indium particles. Turn on the nitrogen gun to dry the indium particles after they have been soaked and cleaned with acetone until there is no obvious acetone liquid residue on the surface of the indium particles. Then turn off the nitrogen gun.

[0037] S2. Operators should wear corrosion-resistant nitrile gloves and KN95 respirators as required. The preparation should be carried out in a fume hood. Accurately measure 120 ml of anhydrous ethanol using a 500 ml graduated cylinder and slowly pour it into a dry beaker. Then, measure 40 ml of hydrochloric acid solution using a 50 ml graduated cylinder and slowly pour it into the anhydrous ethanol along the beaker wall while continuously stirring clockwise with a glass rod at a speed of 30 r / min to ensure that the two reagents are mixed evenly. The prepared hydrochloric acid-anhydrous ethanol mixture should be placed in a fume hood for later use.

[0038] After step S1, move the indium granules along with the beaker to the fume hood. Pour the pre-prepared hydrochloric acid-anhydrous ethanol mixture into the beaker, ensuring that the indium granules are completely submerged in the cleaning solution. Start the timer. During the soaking process, every 1.5 minutes, gently shake the beaker 5 times by holding the bottom, with each shaking lasting 10 seconds. After soaking for 10 minutes, slowly pour the hydrochloric acid mixture into the waste acid recycling tank.

[0039] Pour 250 ml of anhydrous ethanol into a beaker containing indium granules, hold the beaker and gently shake for 15 seconds to ensure that the indium granules are in full contact with the ethanol. Then pour the ethanol into a dedicated anhydrous ethanol recovery container. Repeat this rinsing operation three times. After the last rinse, pour 250 ml of anhydrous ethanol into the beaker again, soak for 5 minutes, and then pour the ethanol into the recovery container.

[0040] Hold the nitrogen gun again, with the nozzle facing the indium granules in the beaker, maintaining a distance of 20cm. Turn on the nitrogen gun and blow air for 3 minutes. During this time, closely observe the stability of the beaker to avoid it tipping over due to the impact of the airflow.

[0041] S3. Take a clean plasma cleaning rack, apply a small amount of anhydrous ethanol to a lint-free cloth, and wipe the surface of the rack evenly. Place it on a clean workbench to dry. Cut a suitable size of high-vacuum aluminum foil and lay it on the surface of the cleaning rack. Gently wipe the surface of the aluminum foil with a lint-free cloth soaked in anhydrous ethanol. After the ethanol has completely evaporated, slowly pour the indium particles from step S2 onto the plasma cleaning rack. Turn on the power of the plasma cleaner, select the preset program for indium particle cleaning, set the plasma cleaner to a power of 200 W, a frequency of 13.56 MHz, and a cleaning time of 5 minutes. Place the plasma cleaning rack carrying the indium particles into the plasma cleaning chamber, close the chamber door, start the cleaning program, and after the program has automatically completed, open the chamber door and remove the plasma cleaning rack.

[0042] S4. After cleaning, the indium particles are inspected for quality. The standard for qualified indium particle cleaning is: the indium particles are in a completely aggregated state, forming an integral agglomerate, with no dispersed individual indium particles present; the surface of the indium particles has a uniform silvery-white metallic luster, presenting a typical metallic bright appearance.

[0043] Indium particles that pass the cleaning process will proceed to the next step; indium particles that fail the cleaning process will be cleaned again, and those that still fail the cleaning process will be scrapped.

[0044] Comparative Example 1 As described in Example 1, the difference is: The steps of soaking and cleaning the indium particles in acetone and drying them with nitrogen in step S1 are omitted; other conditions and steps are the same as in Example 1.

[0045] Comparative Example 2 As described in Example 1, the difference is: The indium particles were not soaked and cleaned with a hydrochloric acid-anhydrous ethanol mixture in step S2. Other conditions and steps were the same as in Example 1.

[0046] Comparative Example 3 As described in Example 1, the difference is: The plasma cleaning operation in step S3 is omitted, and the other conditions and steps are the same as in Example 1.

[0047] Test case One hundred batches of indium particles were cleaned using the cleaning methods of Examples 1-2 and Comparative Examples 1-3. The quality of each batch of indium particles was inspected, and the results are shown in Table 1.

[0048] Table 1 As shown in Table 1, the pass rate of the cleaning methods in Examples 1-2 is significantly higher than that in Comparative Examples 1-3, indicating that the cleaning method of the present invention, by combining acetone, hydrochloric acid-anhydrous ethanol mixture and plasma cleaning, can effectively remove different types of contaminants on the surface of indium particles and significantly improve the cleaning effect of indium particles.

Claims

1. A method for cleaning indium granules used in semiconductor laser packaging, characterized in that, Includes the following steps: S1. The indium particles are soaked and cleaned with acetone, and then dried with nitrogen. S2. The indium particles cleaned in step S1 are soaked and cleaned in a mixture of hydrochloric acid and anhydrous ethanol, then rinsed with anhydrous ethanol, then soaked and cleaned again with anhydrous ethanol, and finally dried with nitrogen. S3. Perform plasma cleaning on the indium particles after cleaning in step S2. S4. Perform a quality inspection on the indium particles after cleaning in step S3 to determine whether the indium particles are qualified for cleaning.

2. The cleaning method for indium particles used in semiconductor laser packaging according to claim 1, characterized in that, In step S1, the mass-to-volume ratio (g / ml) of indium particles to acetone is 1:(1-4); the immersion and cleaning time in acetone is 30-50 seconds.

3. The cleaning method for indium granules used in semiconductor laser packaging according to claim 1, characterized in that, In step S2, the mass-volume ratio (g / ml) of indium particles to hydrochloric acid-anhydrous ethanol mixture is 1:(1.25-2).

4. The cleaning method for indium granules used in semiconductor laser packaging according to claim 1, characterized in that, In step S2, the volume ratio of hydrochloric acid to anhydrous ethanol in the hydrochloric acid-anhydrous ethanol mixture is 3:(5-20), and the mass concentration of hydrochloric acid is 35%-45%.

5. The cleaning method for indium particles used in semiconductor laser packaging according to claim 1, characterized in that, In step S2, the soaking and cleaning time with hydrochloric acid-anhydrous ethanol mixture is 5-10 minutes, and the mixture is shaken every 1-2 minutes.

6. The cleaning method for indium particles used in semiconductor laser packaging according to claim 1, characterized in that, In step S2, the rinsing is performed 3-5 times with anhydrous ethanol, with each rinse using 250-400 ml of anhydrous ethanol.

7. The cleaning method for indium particles used in semiconductor laser packaging according to claim 1, characterized in that, In step S2, the sample is soaked and cleaned with anhydrous ethanol for 3-5 minutes, and the amount of anhydrous ethanol used for soaking and cleaning is 250-400ml.

8. The cleaning method for indium particles used in semiconductor laser packaging according to claim 1, characterized in that, In step S3, the plasma cleaning time is 5-10 minutes, and the power of the plasma cleaner is 150-200W and the frequency is 13.56 MHz ± 0.1%.

9. The cleaning method for indium particles used in semiconductor laser packaging according to claim 1, characterized in that, In step S4, the standard for qualified indium particle cleaning is: the indium particles are in a completely aggregated state, forming an integral agglomerate, with no dispersed individual indium particles present; the surface of the indium particles has a uniform silvery-white metallic luster, presenting a typical metallic bright appearance.

10. The cleaning method for indium particles used in semiconductor laser packaging according to claim 1, characterized in that, In step S4, if the indium particles are cleaned to the qualified level, the next process can be carried out; if the indium particles are not cleaned to the qualified level, they need to be cleaned again, and if they are still not qualified after cleaning, they are scrapped.

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