Chip unsealing method

Abstract

The invention provides a chip unsealing method, and relates to the technical field of semiconductor devices, and the chip unsealing method comprises the following steps: placing a PCB in a first corrosive liquid at a first preset temperature until a packaging layer is dissolved, and enabling a to-be-unsealed chip to be separated from the PCB; putting the to-be-unsealed chip into a second corrosive liquid at a second preset temperature until the polymeric membrane on the surface of the to-be-unsealed chip is dissolved; and taking out the chip. According to the technical scheme, the problem of unsealing of the chip embedded in the PCB can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a chip unsealing method. Background Art

[0002] Existing chip packaging primarily consists of epoxy molding compounds, metal packaging, and ceramic packaging, with corresponding methods for decapsulation, such as laser, chemical, and mechanical. For plastic-encapsulated devices, the commonly used method is a wet chemical acid decapsulation method. However, for chips embedded in PCBs, since the PCB and the encapsulation layer are mostly made of PP (polypropylene) and copper foil, and the chip surface is covered by a polymer film, the original single recipe cannot completely remove the chip. Summary of the Invention

[0003] The main purpose of the present invention is to provide a chip unsealing method, aiming to solve the unsealing problem of chips embedded in PCBs.

[0004] To achieve the above-mentioned purpose, the present invention proposes a chip unsealing method, comprising: placing the PCB in a first etching solution at a first preset temperature until the encapsulation layer dissolves and the chip to be unpacked is separated from the PCB; placing the chip to be opened into a second etching solution at a second preset temperature until the polymer film on the surface of the chip to be opened dissolves; Remove the chip.

[0005] In one embodiment of the present application, the first etching solution is a mixed acid solution of nitric acid and sulfuric acid.

[0006] In one embodiment of the present application, the nitric acid is fuming nitric acid, and the sulfuric acid is sulfuric acid having a mass fraction greater than or equal to 70%; And / or, the nitric acid accounts for 85%-95%, and the sulfuric acid accounts for 15%-5%.

[0007] In one embodiment of the present application, the second etching solution is sulfuric acid with a mass fraction greater than or equal to 70%.

[0008] In one embodiment of the present application, the first preset temperature is 120° C. to 170° C.; And / or, the second preset temperature is 120°C to 180°C.

[0009] In one embodiment of the present application, the step of placing the PCB in a first etching solution at a first preset temperature until the encapsulation layer dissolves and the chip to be unsealed is separated from the PCB includes: Placing the PCB in a first etching solution at a first preset temperature for a first preset time until the encapsulation layer dissolves and the chip to be unpacked is separated from the PCB, wherein the first preset time is 5 seconds to 25 seconds; And / or, the step of placing the chip to be unsealed in a second etching solution at a second preset temperature until the polymer film on the surface of the chip to be unsealed is dissolved comprises: The chip to be opened is placed in a second etching solution at a second preset temperature for a second preset time until the polymer film on the surface of the chip to be opened is dissolved, and the second preset time is 40 seconds to 2000 seconds.

[0010] In one embodiment of the present application, after the step of placing the PCB in a first etching solution at a first preset temperature until the encapsulation layer dissolves and the chip to be unpacked is separated from the PCB, the step further includes: Clean and dry the chip to be opened.

[0011] In one embodiment of the present application, the step of cleaning and drying the chip to be unpacked includes: Pour out the liquid from the container; Add water to the container to wash the chips to be opened; Take out the chip to be opened and dry it.

[0012] In one embodiment of the present application, the step of removing the chip includes: Pour out the liquid from the container; Add water to the container to wash the chips to be opened; And / or, the step of removing the chip includes: Use a plastic dropper to remove the chip from the container.

[0013] In one embodiment of the present application, after the step of removing the chip, the method further includes: Place the chip in the cleaning solution for cleaning; And / or, before the step of placing the PCB in a first etching solution at a first preset temperature until the encapsulation layer dissolves and the chip to be unpacked is separated from the PCB, the step further includes: Clean the PCB.

[0014] The technical solution of the present invention uses a first etching solution to decompose the encapsulation layer on the chip surface, thereby removing the chip to be unsealed from the PCB. A second etching solution is then used to decompose the polymer film on the chip surface, completing the chip unsealing. In other words, the technical solution of the present invention uses different etching solutions with specific formulations to specifically decompose the encapsulation layer and the polymer film used to encapsulate the chip, allowing the chip to be cleanly removed, thus solving the problem of unsealing chips embedded in the PCB. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0016] Figure 1 This is a flow chart of a first embodiment of a chip unsealing method according to the present invention; Figure 2 This is a flow chart of a second embodiment of the chip unsealing method of the present invention; Figure 3 This is a flow chart of a third embodiment of the chip unsealing method of the present invention; Figure 4 This is a flow chart of a fourth embodiment of a chip unsealing method according to the present invention; Figure 5 This is a flow chart of a fifth embodiment of the chip unsealing method of the present invention; Figure 6 This is a flow chart of a sixth embodiment of the chip unsealing method of the present invention; Figure 7 This is a flow chart of a seventh embodiment of the chip unsealing method of the present invention; Figure 8 This is a flow chart of an eighth embodiment of the chip unsealing method of the present invention; Figure 9 This is a flow chart of a ninth embodiment of the chip unsealing method of the present invention; Figure 10 This is a flowchart of the tenth embodiment of the chip unsealing method of the present invention; Figure 11 Flowchart of the eleventh embodiment of the chip unsealing method of the present invention; Figure 12 This is a flow chart of the twelfth embodiment of the chip unsealing method of the present invention; Figure 13 This is a flow chart of a thirteenth embodiment of the chip unsealing method of the present invention; Figure 14 This is a flow chart of the fourteenth embodiment of the chip unsealing method of the present invention.

[0017] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0020] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0021] In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] The present invention provides a chip unsealing method.

[0023] Please refer to Figure 1 In some embodiments of the present application, the chip unsealing method includes the following steps: Step S10, placing the PCB in a first etching solution at a first preset temperature until the encapsulation layer is dissolved and the chip to be unpacked is separated from the PCB; Step S30, placing the chip to be opened into a second etching solution at a second preset temperature until the polymer film on the surface of the chip to be opened is dissolved; Step S50: taking out the chip.

[0024] The chip unsealing method proposed in the present application is mainly used for unsealing chips embedded in PCBs, that is, the chip needs to be removed from the PCB, and the polymer film on the surface of the chip needs to be decomposed to obtain a clean chip. Specifically, the chip is generally packaged in the PCB by epoxy molding compound packaging, metal packaging and ceramic packaging. At this time, the first corrosive liquid can be configured in a targeted manner, and the first corrosive liquid can be maintained at a first preset temperature according to the preferred corrosion temperature of the first corrosive liquid. For example, the first corrosive liquid can be a strong acid such as concentrated sulfuric acid, concentrated nitric acid, or a mixed solution of at least two acidic solutions. The PCB is placed in the first corrosive liquid. When it is observed that the PCB has decomposed to produce the chip to be unsealed, the chip to be unsealed is taken out of the first corrosive liquid and placed in the second corrosive liquid to reduce the immersion time of the chip to be unsealed in the first corrosive liquid. The second corrosive liquid can also be configured according to the material of the polymer film on the surface of the chip. At the same time, the second corrosive liquid can be maintained at a second preset temperature according to the preferred corrosion temperature of the second corrosive liquid to speed up the unsealing. The polymer film on the surface of the chip is decomposed, thereby quickly obtaining a clean chip, reducing the chip's immersion time in the second etching solution, and preventing the second etching solution from damaging the chip. Generally speaking, since the encapsulation layer and the polymer film on the chip surface are made of different materials, the first etching solution and the second etching solution generally have different compositions. Different etching solutions are configured according to the materials of the encapsulation layer and the polymer film, respectively, to improve the chip unsealing efficiency. At this time, after the chip to be unsealed is peeled from the PCB in the first etching solution, it can be first cleaned and dried as described in the following embodiment before being placed in the second etching solution. This prevents the first etching solution on the surface of the chip to be unsealed from reacting with the second etching solution or affecting the composition ratio and quality of the second etching solution, thereby ensuring the chip unsealing rate in the second etching solution. After the polymer film on the chip surface has completely decomposed, the chip is removed and cleaned to prevent residual etching solution on the chip surface from causing damage to the user when testing the chip.

[0025] Therefore, it can be understood that the technical solution of the present invention utilizes a first etching solution to decompose the encapsulation layer on the chip surface, thereby removing the chip to be unsealed from the PCB; then, a second etching solution is used to decompose the polymer film on the chip surface, completing the chip unsealing. In other words, the technical solution of the present invention utilizes different etching solutions with specific formulations to specifically decompose the encapsulation layer and the polymer film used to encapsulate the chip, allowing the chip to be cleanly removed, thus solving the problem of unsealing chips embedded in the PCB.

[0026] In some embodiments of the present application, the first etching solution is a mixed acid solution of nitric acid and sulfuric acid.

[0027] In this embodiment, the first etching solution includes nitric acid and sulfuric acid, and the volume ratio can be adjusted according to the material of different chips. Nitric acid is a strong acid with strong oxidizing and corrosive properties. Using nitric acid and sulfuric acid as a mixed solution can dilute the nitric acid with sulfuric acid, thereby reducing the corrosive performance of the first etching solution. Therefore, the packaging layer can be quickly dissolved to quickly remove the chip to be unsealed, and the damage to the chip by the etching solution can be effectively avoided.

[0028] In some embodiments of the present application, the first corrosive acid is fuming nitric acid, and the sulfuric acid is an aqueous solution of sulfuric acid having a mass fraction greater than or equal to 70%; And / or, the nitric acid accounts for 85%-95%, and the sulfuric acid accounts for 15%-5%.

[0029] In this embodiment, nitric acid uses fuming nitric acid, that is, a solution containing 90% to 97.5% nitric acid, and sulfuric acid uses concentrated sulfuric acid, that is, sulfuric acid with a mass fraction greater than or equal to 70%. The mixed acid prepared by fuming nitric acid and concentrated sulfuric acid has strong corrosiveness and a high desealing rate, and can complete corrosion decomposition in a short time.

[0030] In addition, sulfuric acid can be used to dilute nitric acid in the first etching solution to reduce the corrosive performance of the first etching solution. In this embodiment, the proportion of nitric acid in the first etching solution is 85%-95%, and the corresponding proportion of sulfuric acid in the first etching solution is 15%-5%. That is, the proportion of nitric acid can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, or any value between 85% and 95%, and the corresponding proportion of sulfuric acid is 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, etc.; in this case, it can ensure that the first etching solution maintains a high corrosion decomposition rate on the encapsulation layer, and can effectively prevent the first etching solution from being too corrosive and causing damage to the chip.

[0031] In some embodiments of the present application, the second etching solution is sulfuric acid with a mass fraction greater than or equal to 70%.

[0032] In this embodiment, the second etching solution is concentrated sulfuric acid with a mass fraction greater than or equal to 70%. Using concentrated sulfuric acid to corrode the polymer film on the chip surface can complete the corrosion decomposition in a short time, thereby improving the chip unsealing efficiency.

[0033] In some embodiments of the present application, the first preset temperature is 120° C. to 170° C.; And / or, the second preset temperature is 120°C to 180°C.

[0034] The technical solution of the present application sets a first preset temperature based on the optimal reaction temperature of the first etching liquid and the encapsulation layer, and maintains the temperature of the first etching liquid at the first preset temperature so that the first etching liquid can quickly decompose the encapsulation layer on the surface of the chip to be unsealed, thereby increasing the chip separation speed. In this embodiment, the first preset temperature is set to 120°C to 170°C. In this way, the first etching liquid accelerates the corrosion of the encapsulation layer by heating, thereby improving the efficiency of separating the chip from the PCB. The first preset temperature can be 120°C, 130°C, 140°C, 145°C, 150°C, 155°C, 160°C, 170°C, and any value between 120°C and 170°C, and is not specifically limited here.

[0035] Similarly, a second preset temperature is set based on the optimal reaction temperature between the second etching solution and the polymer film on the chip surface, and the temperature of the second etching solution is maintained at the second preset temperature so that the second etching solution can decompose the polymer film more quickly. In this embodiment, the second preset temperature is set to 120°C to 180°C. This setting accelerates the decomposition of the polymer film by the second etching solution through heating, thereby improving the chip opening efficiency, reducing the chip immersion time in the second etching solution, and reducing the risk of the chip being corroded and damaged by the second etching solution. The second preset temperature can be 120°C, 130°C, 140°C, 145°C, 150°C, 155°C, 160°C, 170°C, 180°C, or any value between 120°C and 180°C, and is not specifically limited here.

[0036] Please refer to Figure 2 In some embodiments of the present application, the step of placing the PCB in a first etching solution at a first preset temperature until the packaging layer dissolves and the chip to be unpacked is separated from the PCB includes: Step S11: placing the PCB in a first etching solution at a first preset temperature for a first preset time until the packaging layer dissolves and the chip to be unpacked is separated from the PCB. The first preset time is 5 seconds to 25 seconds.

[0037] It is understood that the first etching solution is maintained at a temperature between 120°C and 170°C during decomposition to increase the decomposition rate of the chip surface packaging layer. In this embodiment, when the PCB is placed in the first etching solution for etching, the first etching solution is continuously heated to maintain the first etching solution at a first preset temperature. This allows the first etching solution to maintain an optimal etching rate during the etching process of the packaging layer, preventing the first etching solution from dropping in temperature over time, which would otherwise prolong the etching time.

[0038] In addition, since the chip is embedded in the PCB, and as electronic products continue to develop in the direction of small size and dense circuits, the size of the chip is also getting smaller and smaller. This poses the problem of the user being unable to accurately determine with the naked eye whether the chip has completely detached from the PCB. In this embodiment, the etching time of the PCB in the first etching solution is pre-set. Since the temperature of the first etching solution is always maintained within a first preset temperature range, the rate at which the packaging layer is corroded by the first etching solution can be estimated based on the package type and the composition of the first etching solution. The time it takes for the packaging layer to be corroded and decomposed can then be calculated as the first preset time. After the PCB has been immersed in the first etching solution for the first preset time, it can be determined that the chip to be unsealed has detached from the PCB, eliminating the need for the user to observe with the naked eye, thereby improving the operational convenience of the unsealing process. In some embodiments, since the unsealing time can be pre-set, the chip to be unsealed can also be automatically removed after the preset time is reached by a robot or other means, thereby improving the degree of automation.

[0039] In this embodiment, the first preset time is defined as 5s to 25s. Generally speaking, due to the small size of the chip, the area and thickness of the packaging layer are also relatively small. The etching time of 5s to 25s is sufficient to corrode the packaging layer and cause the chip to fall off. The immersion time of the chip to be unsealed in the first etching solution should not exceed 25s to prevent the first etching solution from damaging the chip to be unsealed. The specific immersion time can be calculated and set based on the chip packaging type and the composition of the first etching solution.

[0040] Please refer to Figure 3 In some embodiments of the present application, the step of placing the chip to be unsealed in a second etching solution at a second preset temperature until the polymer film on the surface of the chip to be unsealed is dissolved includes: Step S31 , placing the chip to be opened in a second etching solution at a second preset temperature for a second preset time until the polymer film on the surface of the chip to be opened is dissolved, wherein the second preset time is 40 seconds to 200 seconds.

[0041] As can be understood, the technical solution of the above embodiment maintains the second etching solution at a temperature between 120°C and 180°C during decomposition, thereby increasing the decomposition rate of the polymer film on the chip surface. In this embodiment, when the chip to be opened is placed in the second etching solution for etching, the second etching solution is continuously heated to maintain the second etching solution at a second preset temperature. This allows the second etching solution to maintain an optimal etching rate during the etching process of the polymer film, preventing the second etching solution temperature from dropping over time, which would extend the etching time.

[0042] Furthermore, as electronic products continue to develop towards smaller sizes and denser circuits, chip sizes are also shrinking, posing the problem of users being unable to accurately discern with the naked eye whether the polymer film on the chip surface has been completely decomposed. In this embodiment, the etching time of the chip to be unsealed is pre-set in the second etching solution. Since the temperature of the second etching solution is always maintained within a second preset temperature range, the rate at which the polymer film is corroded by the second etching solution can be estimated based on the material of the polymer film and the composition of the second etching solution. The time it takes for the polymer film to be corroded and decomposed is then calculated as the second preset time. After the chip to be unsealed has been immersed in the second etching solution for the second preset time, it can be determined that the polymer film on the chip surface has been removed, eliminating the need for the user to visually inspect the chip, thereby improving the operational convenience of the unsealing process.

[0043] In this embodiment, the second preset time is 40 seconds to 200 seconds. This means that the chip to be opened is immersed in the second etching solution for at least 40 seconds, thereby ensuring that the polymer film on the surface of the chip to be opened is fully decomposed. Furthermore, the chip to be opened is immersed in the second etching solution for a time period exceeding 200 seconds to prevent the chip from being exposed to the second etching solution for a long time after the polymer film on the chip surface is decomposed, thereby causing corrosion damage. The specific immersion time of the chip in the second etching solution can be calculated and set based on the actual chip type and the concentration of the components in the second etching solution, and is not further described here.

[0044] Please refer to Figure 8 In some embodiments of the present application, after the step of placing the PCB in a first etching solution at a first preset temperature until the packaging layer dissolves and the chip to be unpacked is separated from the PCB, the following steps are included: Step S20: cleaning and drying the chip to be unpacked.

[0045] It can be understood that the technical solution of the present application utilizes two etching solutions with different components or material ratios to respectively etch the encapsulation layer of the packaged chip and the polymer film on the chip surface, so that the chip can be removed from the PCB and cleanly unsealed. In this embodiment, after the chip to be unsealed is peeled from the PCB in the first etching solution, the chip needs to be cleaned and dried to prevent the first etching solution contaminated on the chip surface from mixing with the second etching solution, thereby preventing the first etching solution from reacting with the second etching solution or affecting the composition ratio and quality of the second etching solution, thereby ensuring the unsealing rate of the chip in the second etching solution and allowing the second etching solution to be reused.

[0046] Please refer to Figure 9 In some embodiments of the present application, the step of cleaning and drying the chip to be unpacked includes: Step S21, pouring out the liquid in the container; Step S23, adding water to the container to wash the chips to be opened; Step S25: taking out the chips to be opened and performing drying.

[0047] Specifically, after the chip is removed from the PCB, the first etching liquid in the container is poured out, leaving only the PCB, the chip to be opened, and the corroded solid residues in the container. Of course, the first etching liquid can be completely poured out, but because the solid residue or the container wall may be contaminated with the first etching liquid, or in order to prevent the chip to be opened from being poured out together, a small amount of the first etching liquid may remain in the container; after pouring out the first etching liquid in the container, water is added to the container so that the residue remains in water that is almost acid-free, and then the solid residue is washed. The water added can be but is not limited to pure water, distilled water, deionized water or clean water, and the washing process is similar to the operation of washing rice; in addition, please refer to Figure 10 The above operation can be repeated, that is, after washing the fixed residue, pour out the liquid in the container and re-add pure water, distilled water, deionized water or clean water to wash the solid residue to ensure that the residue remains in pure water with almost no acid. Generally, the above purpose can be achieved after washing twice, and then the chip to be opened in the container can be taken out for subsequent drying treatment.

[0048] In some embodiments of the present application, the step of adding water to the container to clean the chip to be opened includes: Add water to the container to fill more than 2 / 3 of the container volume to clean the chip to be opened.

[0049] In this embodiment, in the step of cleaning the unsealed chip, the amount of pure water, distilled water, deionized water or clean water added to the container is at least 2 / 3 of the container volume, thereby ensuring that the added clean water can fully dilute the residual liquid in the container, thereby constructing an almost acid-free environment in the container and ensuring that the first etching solution contaminated by the solid residue is fully removed.

[0050] Please refer to Figure 11 In some embodiments of the present application, the step of removing the unsealed chip for drying includes: Use a plastic dropper to suck the chip remaining in the container onto the dropper tip and transfer it to the filter paper.

[0051] Understandably, as electronic products continue to develop toward smaller sizes and denser circuits, chips are becoming increasingly smaller and thinner, making chip transfer and handling extremely difficult. Improper transfer and handling methods can damage the chip. Furthermore, the etching solution used during chip unpacking is typically a strong acid. Slow chip removal, resulting in the chip remaining in the etching solution for too long, can also damage the chip. In this embodiment, a plastic dropper is used to remove and place the chip. The small opening of the plastic dropper is compatible with the chip size, allowing for better chip suction. The chip is only subject to suction, effectively avoiding issues such as unstable gripping resulting in the chip remaining in the container for extended periods or excessive clamping force that can damage the chip. Compared to tweezers, this approach avoids issues such as unstable gripping resulting in the chip remaining in the container for extended periods or excessive clamping force that can damage the chip. In addition, the use of a plastic dropper can also avoid the problem of the chip being punctured due to the dropper being too hard, thereby allowing for faster and safer transfer and removal of the chip. After the plastic dropper takes out the chip to be opened from the container, the chip to be opened is placed on filter paper. The filter paper can be used to absorb the liquid on the surface of the chip to be opened, making the surface of the chip to be opened dry, thereby preventing the chip to be opened from being contaminated with liquid and causing the liquid to enter the second etching solution along with the chip to be opened.

[0052] Please refer to Figure 11 In some embodiments, in order to facilitate the plastic dropper to suck up the chip to be opened, the liquid in the container can be poured out first to avoid excessive liquid in the container causing the chip to be opened to be easily displaced when the liquid is shaken. In this case, the steps of washing and drying the chip to be opened include: Step S21, pouring out the liquid in the container; Step S23, adding water to the container to wash the chips to be opened; Step S251, pouring out the liquid in the container; Step S253: Use a plastic dropper to suck the remaining chips to be opened in the container to the head of the plastic dropper and transfer them to the filter paper.

[0053] The specific operation steps are not described here.

[0054] Please refer to Figure 4 In some embodiments of the present application, the step of removing the chip includes: Step S41, pouring out the liquid in the container; Step S43: Add water to the container to wash the chip.

[0055] It is understandable that after the polymer film on the surface of the chip is decomposed in the second corrosive liquid, the chip is taken out and cleaned to avoid residual corrosive liquid on the chip surface causing damage to the user when the chip is tested. In this embodiment, after the polymer film on the surface of the chip is decomposed, the second corrosive liquid in the container is poured out, so that only the chip and solid residues such as corrosive materials are left in the container. Of course, the second corrosive liquid can be completely poured out, but since the solid residue or the container wall may be contaminated with the second corrosive liquid, or in order to avoid the chip being poured out together, a small amount of the second corrosive liquid may remain in the container; after pouring out the second corrosive liquid in the container, water is added to the container so that the residue remains in almost acid-free water, and then the solid residue is cleaned, wherein the added water can be but not limited to pure water, distilled water, deionized water or clean water, etc., wherein the cleaning process is similar to the operation of washing rice; in addition, please refer to Figure 7 , you can repeat the above-mentioned water-adding and washing steps, that is, after washing the fixed residues, pour out the liquid in the container and re-add pure water, distilled water, deionized water or clean water to wash the solid residues to ensure that the residues remain in pure water with almost no acid. Generally, the above purpose can be achieved after washing twice, and then the chip in the container can be taken out for subsequent operations.

[0056] In some embodiments of the present application, the step of adding water to the container to wash the chip includes: Add water to the container to fill more than 2 / 3 of the container volume to clean the chip.

[0057] In this embodiment, in the step of cleaning the unsealed chip, the amount of pure water, distilled water, deionized water or clean water added to the container is at least 2 / 3 of the container volume, thereby ensuring that the added clean water can fully dilute the residual liquid in the container, thereby constructing an almost acid-free environment in the container and ensuring that the second etching solution contaminated by the solid residue is fully removed.

[0058] Please refer to Figure 5 In some embodiments of the present application, the step of removing the chip includes: In step 51 , a plastic dropper is used to draw the chip from the container.

[0059] As is understandable, as electronic products continue to develop towards smaller sizes and denser circuits, chips are becoming increasingly smaller and thinner, making chip transfer and handling extremely difficult. Improper transfer and handling methods can damage the chip. Furthermore, the etching solution used during chip unsealing is typically a strong acid. Slow chip removal, resulting in the chip remaining in the etching solution for an extended period, can also damage the chip. In this embodiment, a plastic dropper is used to remove and place the chip. The small opening of the plastic dropper is compatible with the chip size, allowing for better chip suction. The chip is only subjected to suction, effectively avoiding issues such as unstable gripping resulting in prolonged chip retention or excessive clamping force that can damage the chip, compared to tweezers. Furthermore, the use of a plastic dropper avoids chip punctures caused by a stiff dropper, allowing for faster and safer chip transfer and handling. After removing the chip from the container with the plastic dropper, the chip can be rinsed or placed on filter paper to absorb liquid from the surface of the unsealed chip, preventing contamination of the chip with the second etching solution.

[0060] Please refer to Figure 6 In some embodiments, to prevent the second corrosive liquid from corroding the plastic dropper, before using the plastic dropper, the aforementioned steps S41 and S43 are performed to ensure that the container is in an acid-free environment. In addition, to facilitate the plastic dropper to absorb the chip, the liquid in the container can be poured out first to prevent the chip from being easily displaced when the liquid is shaken due to excessive liquid in the container. In this case, the following steps can be performed: Step S41, pouring out the liquid in the container; Step S43, adding water to the container to wash the chip; Step S511, pouring out the liquid in the container; In step S513, a plastic dropper is used to suck the chip remaining in the container to the head of the plastic dropper and transfer it to the filter paper.

[0061] The specific operation steps are not described here.

[0062] For further information, please refer to Figure 12 In some embodiments, after the step of removing the chip, the step further includes: Step S70: placing the chip in a cleaning solution for cleaning.

[0063] Such operation can ensure that a clean chip is obtained for detection, wherein the cleaning liquid can be water, alcohol, etc., which is not limited here.

[0064] In some embodiments of the present application, the cleaning fluid is alcohol; And / or, the third preset time for cleaning the chip in the cleaning solution is 1 min to 2 min.

[0065] In this embodiment, alcohol is used as a cleaning liquid to clean the chip after opening. Alcohol has a good decontamination effect and good volatility. It can effectively clean the dirt on the surface of the chip and keep the chip dry after cleaning. At the same time, it will not affect the electrical performance of the chip, avoiding affecting the subsequent testing of the chip.

[0066] In some embodiments, the chip is cleaned in the cleaning solution for 1 to 2 minutes to ensure that dirt attached to the chip is completely removed and to avoid excessive cleaning time.

[0067] Please refer to Figure 13 In some embodiments of the present application, the step of placing the PCB in a first etching solution at a first preset temperature until the chip to be unsealed is detached includes: Step S01, cleaning the PCB.

[0068] In this embodiment, before placing the PCB in the first etching solution to remove the chip to be opened, the PCB is first cleaned to prevent dust and other impurities from entering the first etching solution along with the PCB, thereby affecting the quality of the first etching solution and the etching rate of the packaging layer. The PCB cleaning operation can be performed by wiping the PCB or using a rice-washing cleaning method as in the above embodiment, or by using an ultrasonic cleaner or other tool as in the following embodiment, without limitation.

[0069] Please refer to Figure 14 In some embodiments of the present application, the step of cleaning the PCB includes: Step S03: using IPA to ultrasonically clean the PCB.

[0070] In this embodiment, before placing the PCB in the first etching solution to separate the chip to be opened, the PCB is ultrasonically cleaned using IPA. The basic principle of ultrasonic cleaning technology is to use the huge force generated by the ultrasonic field, in conjunction with the cleaning medium, to promote a series of physical and chemical changes in the substance to achieve the purpose of cleaning. The use of IPA (isopropyl alcohol) ultrasonic cleaning of the PCB includes four processes: washing, rinsing, dehydration, and drying. During the washing process, the PCB is placed in the cleaning medium of the ultrasonic cleaning instrument. After the high-frequency vibration generated by the ultrasonic field is transmitted to the cleaning medium, the liquid medium generates a nearly vacuum cavity bubble under the high-frequency vibration. The cavity bubble is The collision, merging, and annihilation of these bubbles can cause localized pressures of several thousand atmospheres to surge. This intense pressure triggers a series of physical and chemical changes in the surrounding material. The shockwaves generated by the sudden closure of the cavity can generate pressures of thousands of atmospheres around it. These repeated impacts on the dirt layer adhering to the PCB disrupt the dirt's adsorption to the PCB surface and, at the same time, break the dirt layer apart, releasing it from the surface and dispersing it into the cleaning fluid. The vibration of the bubbles can also scrub solid surfaces. Ultrasonic cleaning can also clean gaps between components on the PCB, thoroughly cleaning the PCB. After cleaning, the PCB is rinsed with running water to dissolve and remove any detergent and dirt adhering to the surface. The rinsed PCB is then placed in IPA. The high-frequency ultrasonic vibrations rapidly and thoroughly dissolve the detergent and IPA on the PCB surface, making the surface the same as the mixed IPA, thereby dehydrating the PCB. The PCB is then condensed, causing the IPA on the surface to liquefy and release, drying the PCB and completing the cleaning process.

[0071] In some embodiments of the present application, the fourth preset time for ultrasonically cleaning the PCB using IPA is 3 to 7 minutes.

[0072] In this embodiment, the IPA ultrasonic cleaning time of the PCB is set to at least 3 minutes to ensure that dirt and the like on the PCB can be completely cleaned. In addition, the cleaning time is set to no more than 7 minutes to avoid affecting the chip unsealing efficiency due to excessive cleaning time.

[0073] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A chip unsealing method, characterized in that: include: placing the PCB in a first etching solution at a first preset temperature until the encapsulation layer dissolves and the chip to be unpacked is separated from the PCB; placing the chip to be opened into a second etching solution at a second preset temperature until the polymer film on the surface of the chip to be opened is dissolved; Remove the chip.

2. The chip unsealing method according to claim 1, wherein: The first etching solution is a mixed acid solution of nitric acid and sulfuric acid.

3. The chip unsealing method according to claim 2, wherein: The nitric acid is fuming nitric acid, and the sulfuric acid is sulfuric acid having a mass fraction greater than or equal to 70%; And / or, the nitric acid accounts for 85%-95%, and the sulfuric acid accounts for 15%-5%.

4. The chip unsealing method according to claim 1, wherein: The second etching solution is sulfuric acid with a mass fraction greater than or equal to 70%.

5. The chip unsealing method according to claim 1, wherein: The first preset temperature is 120°C to 170°C; And / or, the second preset temperature is 120°C to 180°C.

6. The chip unsealing method according to claim 1, wherein: The step of placing the PCB in a first etching solution at a first preset temperature until the packaging layer dissolves and the chip to be unpacked is separated from the PCB includes: Placing the PCB in a first etching solution at a first preset temperature for a first preset time until the encapsulation layer dissolves and the chip to be unpacked is separated from the PCB, wherein the first preset time is 5 seconds to 25 seconds; And / or, the step of placing the chip to be unsealed in a second etching solution at a second preset temperature until the polymer film on the surface of the chip to be unsealed is dissolved comprises: The chip to be opened is placed in a second etching solution at a second preset temperature for a second preset time until the polymer film on the surface of the chip to be opened is dissolved, and the second preset time is 40S to 200S.

7. The chip unsealing method according to claim 1, wherein: After the step of placing the PCB in a first etching solution at a first preset temperature until the packaging layer is dissolved and the chip to be unpacked is separated from the PCB, the following step further comprises: Clean and dry the chip to be opened.

8. The chip unsealing method according to claim 7, wherein: The steps of cleaning and drying the chip to be unpacked include: Pour out the liquid from the container; Add water to the container to wash the chips to be opened; Take out the chip to be opened and dry it.

9. The chip unsealing method according to claim 1, wherein: The step of removing the chip includes: Pour out the liquid from the container; Add water to the container to wash the chip; And / or, the step of removing the chip includes: Use a plastic dropper to remove the chip from the container.

10. The chip unsealing method according to any one of claims 1 to 9, characterized in that: After the step of removing the chip, the following steps are further included: Place the chip in the cleaning solution for cleaning; And / or, before the step of placing the PCB in a first etching solution at a first preset temperature until the encapsulation layer dissolves and the chip to be unpacked is separated from the PCB, the step further includes: Clean the PCB.

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