Method for removing wettability side wing QFN burrs

Abstract

The invention provides a method for removing wettability side wing QFN burrs, and the method comprises the steps: S1, carrying out the plastic packaging of a chip according to a QFN packaging technology, and pasting a transparent anti-acid UV film on the back surface of a QFN frame after plastic packaging; s2, carrying out primary cutting on the QFN frame pasted with the anti-acid UV film; s3, the cut QFN frame is placed in a copper burr cleaning solution for chemical etching; s4, after chemical etching is completed, the QFN frame is taken out to be cleaned and dried, and then the QFN frame and the anti-acid UV film are subjected to UV light irradiation treatment; s5, after the UV light irradiation treatment, pasting an adhesive film on the surface of the anti-acid UV film, and removing the adhesive film to realize the separation of the anti-acid UV film and the QFN frame; and S6, electroplating, marking and secondary cutting are carried out. According to the method, the bad problems of tin whisker generation, short circuit and the like in the electroplating process due to burrs are solved, and the appearance consistency and quality of products are guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor integrated circuit packaging and relates to a method for removing wettable flank QFN burrs. Background Art

[0002] With the continuous development of the quad flat no-lead package (QFN), in order to better solve the problem of being unable to confirm the quality of solder joints and the difficulty in detection after the device is mounted on the printed circuit board (PCB), the wettable flank QFN came into being. Compared with the traditional QFN package pin structure, the improved package side structure is specially designed to form a good side wetting angle, thereby improving the side tinning ability, and the tin climbing height can reach more than 50% of the flank pin length. After welding, the automatic optical inspection (AOI) technology can be used to detect the quality of the solder joints, which is conducive to improving welding reliability and can better meet the needs of high-reliability applications.

[0003] The two-step cutting method is one of the ways to achieve wettable flank QFN. It is based on the existing QFN packaging process and divides the traditional cutting process into two steps. The first cutting exposes part of the flank pins for electroplating, and the second cutting separates the devices. Through two cuttings with different cutting widths, a step shape is formed on the flank pins, thereby achieving a tin climbing height of more than 50% of the length of the flank pins.

[0004] The main problems with the above two-step cutting method are: (1) After the first cut exposes part of the flank pins, cutting path burrs will be generated due to cutting the copper material at the pins. When the cutting depth reaches the connecting rib depth, the connecting rib copper material will be exposed. At this time, as the cutting depth increases, the width of the cutting path burrs will further increase. The generation of burrs will cause problems such as tin whiskers or short circuits during the electroplating process, seriously affecting the consistency and quality of the product appearance. (2) During the first cut, burrs will also be generated at the pins, which may cause tin whiskers to be generated in the subsequent electroplating process, affecting the neat appearance of the chip pins, and in serious cases, may affect the electrical performance of the chip. Summary of the invention

[0005] Aiming at the problem that burrs are easily generated on the cutting path and the pins in one-step cutting in a two-step cutting method for wettable flank QFN, the present invention proposes a method for removing burrs on the wettable flank QFN, thereby solving the problems of tin whiskers and short circuits generated in the electroplating process due to the burrs, and ensuring the appearance consistency and quality of the product.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for removing wettable flank QFN burrs, comprising the following steps:

[0008] S1, plastic-encapsulating the chip according to the QFN packaging process, and after the plastic-encapsulation is completed, pasting a transparent acid-resistant UV film on the back of the plastic-encapsulated QFN frame;

[0009] S2, cutting the QFN frame with the acid-resistant UV film;

[0010] S3, placing the cut QFN frame in a copper burr cleaning solution for chemical etching;

[0011] S4, after the chemical etching is completed, the QFN frame is taken out for cleaning and drying, and then the QFN frame and the acid-resistant UV film are subjected to UV light irradiation treatment;

[0012] S5, after the UV light irradiation treatment, a sticky film is attached to the surface of the acid-resistant UV film, and the sticky film is removed to separate the acid-resistant UV film from the QFN frame;

[0013] S6, electroplating, marking, and secondary cutting processes are performed.

[0014] Preferably, in S1, the acid-resistant UV film comprises a substrate layer, an adhesive layer and a release layer, the substrate layer is a PO film or a PET film, the adhesive layer is an acrylic layer, and the release layer is a PET film.

[0015] Preferably, in S1, the acid-resistant UV film has a thickness of 100-150 μm.

[0016] Preferably, in S1, the adhesion of the acid-resistant UV film to the steel plate is: before illumination, the adhesion is ≥650gf / 25mm; after illumination, the adhesion is ≤25gf / 25mm.

[0017] Preferably, in S3, the composition of the copper burr cleaning solution is, by mass percentage, 3%-4% sulfuric acid, 9%-11% hydrogen peroxide, 1.5%-2.5% stabilizer, 0.4%-0.6% brightener, 0.4%-0.6% corrosion inhibitor, and 81.5%-85.5% deionized water.

[0018] Furthermore, the stabilizer is butanediol, the brightener is butanol phosphate, and the corrosion inhibitor is a mixture of dicyandiamide formaldehyde resin and modified polyacrylamide.

[0019] Preferably, in S3, chemical etching is performed at room temperature.

[0020] Preferably, in S3, the chemical etching time is 2-4 minutes.

[0021] Preferably, in S4, the UV light irradiation treatment time is 1-2 min.

[0022] Preferably, in S5, the adhesive film is a tear-off tape.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention firstly adheres a transparent acid-resistant UV film to the back of a QFN frame after plastic sealing, then performs a cutting, and then performs chemical etching to remove the burrs at the cutting path and the pins, so that the burrs at the cutting path and the pins after the one-time cutting can be effectively removed by the method, and at the same time, the acid-resistant UV film can be used as a protective film to protect the copper material at the non-cutting path position, so as to prevent the copper material at the non-cutting path position from being corroded during the chemical etching process. The method of the present invention solves the problems of tin whiskers and short circuits generated during the electroplating process due to the burrs, and can ensure the appearance consistency and quality of the product.

[0025] Furthermore, the present invention preferably selects a suitable acid-resistant UV film with sufficient transparency, moderate thickness, clear visibility of the cutting path, moderate viscosity, and easy removal.

[0026] Furthermore, the copper burr cleaning liquid used in the present invention can achieve successful removal of copper burrs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 Schematic diagram of the acid-resistant UV film attached to the back of the QFN frame after plastic encapsulation.

[0029] Figure 2 This is a schematic cross-sectional view of the QFN frame after one cutting.

[0030] Figure 3 Schematic diagram of the back side of the QFN frame after one cut.

[0031] Figure 4 Schematic diagram of chemical etching of QFN frame.

[0032] Figure 5 Schematic diagram of using mucus film to remove the UV protective film above the chip.

[0033] Figure 6 This is a schematic diagram of the back of the frame after deburring.

[0034] Figure 7 Pictures of the cutting path before and after deburring.

[0035] In the figure: 1-cutting knife, 2-acid-resistant UV protective film, 3-plastic sealing material, 4-reinforcement ribs, 5-connecting ribs, 6-burrs at the pins, 7-first cutting path, 8-second cutting path, 9-cutting path burrs, 10-copper burr cleaning solution, 11-film peeling. DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0038] It should be noted that the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0039] The method for removing wettable flank QFN burrs of the present invention comprises the following parts:

[0040] (1) Method for selecting the protective film at the bottom of the QFN frame after plastic encapsulation.

[0041] The present invention selects acid-resistant UV film as the protective film. First, the transparent visibility of the film needs to be considered to ensure that the cutting path at the bottom of the QFN frame is clearly visible. Secondly, the viscosity and acid corrosion resistance of the film need to be considered to prevent the copper material at the non-cutting path position from being corroded during the chemical etching process. Finally, the easy removal performance of the film should also be considered. In summary, a transparent acid-resistant UV film is selected as the protective film, and the protective film can be removed by UV removal.

[0042] The acid-resistant UV film has a thickness of 100-150 μm and is an acid-resistant transparent UV anti-viscosity protective film. For example, an acid-resistant UV film with a total thickness of 125 μm is used, and the specific specifications are: total thickness 125 μm, using layer thickness 90 μm (including 80 μm PO substrate, 10 μm modified acrylic adhesive), transparent PET release film 35 μm.

[0043] The acid-resistant UV film used has good adhesion before UV irradiation:

[0044] Adhesion to steel plate - before light exposure (180° peeling, 20min), adhesion ≥ 650gf / 25mm,

[0045] Adhesion to steel plate - after exposure to light (180° peeling, leaving for 20 minutes), adhesion ≤ 25gf / 25mm.

[0046] The acid-resistant UV film used is acid-resistant and alkali-resistant, transparent, has a thin layer thickness and moderate adhesion.

[0047] (2) How to handle the protective film during the first cutting process

[0048] When making the first cut, the protective film is used for cutting. The protective film is only removed at the cutting path, and the protective film at other parts is retained. During cutting, the bottom of the pin is covered by the protective film, so burrs are not easily generated at the pin. After the cutting is completed, chemical etching is performed to remove only the burrs at the cutting path, and other parts are covered by the protective film and are not corroded.

[0049] (3) Method for removing burrs from cutting paths.

[0050] The burrs at the cutting path are removed by chemical etching. The cut QFN frame is placed in a copper burr cleaning solution and chemically etched at room temperature. Based on the product characteristics and with the goal of achieving the best burr removal effect, the concentration of the copper burr cleaning solution and the etching time are adjusted. After the chemical etching is completed, the QFN frame is taken out for cleaning and drying.

[0051] According to mass percentage, the copper burr cleaning solution of the present invention is composed of: 3%-4% sulfuric acid, 9%-11% hydrogen peroxide, 1.5%-2.5% stabilizer, 0.4%-0.6% brightener, 0.4%-0.6% corrosion inhibitor, and 81.5%-85.5% deionized water.

[0052] The stabilizer may be butanediol, the brightener may be butanol phosphate, and the corrosion inhibitor may be a mixture of dicyandiamide formaldehyde resin and modified polyacrylamide. Preferably, the dicyandiamide formaldehyde resin and the modified polyacrylamide are mixed in a mass ratio of 1:1.

[0053] (4) How to remove the protective film

[0054] After the QFN frame is cleaned and dried, a UV irradiator is used to irradiate the protective film to remove the adhesiveness between the protective film and the back of the QFN frame. After that, the QFN frame is placed on an anti-static workbench and an adhesive film is used to cover the top of the protective film to ensure the adhesion between the adhesive film and the protective film. Subsequently, the protective film is removed by removing the protective film attached to the adhesive film, and the subsequent process is continued.

[0055] The adhesive film in the present invention can be a tear-off tape, which is composed of a base material PET and a rubber adhesive.

[0056] Based on the above content, the method for removing wettable flank QFN burrs of the present invention specifically comprises the following steps:

[0057] S1, encapsulate the chip according to the traditional QFN encapsulation process, and after the plastic encapsulation and post-curing are completed, use the acid-resistant UV film 2 to stick it on the back of the QFN frame after the plastic encapsulation; Figure 1 , which is a schematic diagram of an acid-resistant UV film 2 pasted on the back of a QFN frame after plastic sealing, wherein the QFN frame comprises a plastic sealing material 3, reinforcing ribs 4, and connecting ribs 5.

[0058] S2, according to the original one-time cutting process, the QFN frame is cut once using the cutting knife 1; the cross-sectional schematic diagram of the QFN frame after one-time cutting is as follows Figure 2 As shown, a primary cutting line 7 with the same width as the cutting blade 1 is cut out, and a cutting line burr 9 is generated. At the same time, a pin burr 6 is generated at the pin and remains on the acid-resistant UV film 2 ( Figure 3 ).

[0059] S3, placing the cut QFN frame in a copper burr cleaning solution 10, and chemically etching at room temperature to remove the cutting path burrs 9 and the pin burrs 6 ( Figure 4 ).

[0060] S4, after the chemical etching is completed, the QFN frame is taken out for cleaning and drying, and then the QFN frame and the acid-resistant UV film are irradiated with UV light to remove the adhesion of the acid-resistant UV film to the QFN frame;

[0061] S5, stick an adhesive film on the surface of the entire acid-resistant UV film, and remove the adhesive film 11 to separate the acid-resistant UV film from the QFN frame ( Figure 5 ).

[0062] S6, continue with the subsequent electroplating and marking processes, and finally perform secondary cutting. The width of the secondary cutting road is smaller than the width of the primary cutting road 7. The secondary cutting cuts off the connecting rib 5 to achieve device separation.

[0063] The back of the QFN frame treated by the method of the present invention is as follows Figure 6 As shown in the figure, it can be seen that the burrs on the cutting path and the pins have been effectively removed.

[0064] Example 1

[0065] For the QFN3×3×0.75-16L frame, the specific implementation steps are as follows:

[0066] Step 1: For the QFN frame after plastic encapsulation and post-curing by the traditional QFN packaging process, first use a manual film laminating machine to fix the QFN frame on the ring, and then use a transparent acid-resistant UV film with a thickness of 100μm to manually stick it on the back of the plastic-encapsulated QFN frame.

[0067] Step 2: Perform a cut with a cutting width of 0.44 mm, a cutting depth of 0.10 mm, a cooling water flow rate of 3 L / min, a spray water flow rate of 2 L / min, a spindle speed of 28000 r / min, and a feed speed of 30 mm / s.

[0068] Step 3: Place the cut QFN frame in a copper burr cleaning solution for etching for 3 minutes. The cleaning solution ratio is 4.0% sulfuric acid, 11.0% hydrogen peroxide, 2.5% stabilizer butanediol, 0.5% brightener butanol phosphate, 0.5% corrosion inhibitor (a mixture of dicyandiamide formaldehyde resin and modified polyacrylamide in a mass ratio of 1:1), and 81.5% deionized water. After etching, take out the QFN frame for pure water cleaning and oven drying.

[0069] Step 4: Then, the QFN frame and the acid-resistant UV film are irradiated with UV light for 1 minute to remove the adhesion of the acid-resistant UV film to the QFN frame. Then, a tear-off tape is applied to the surface of the entire acid-resistant UV film, and the tear-off tape is removed to separate the acid-resistant UV film from the QFN frame.

[0070] Step 5: The QFN frame that has been deburred is subjected to traditional electroplating and marking treatment. Finally, secondary cutting and separation is performed under the conditions of cooling water flow rate 2L / min, spray water flow rate 2L / min, spindle speed 23000r / min, feed speed 30mm / s, and cutting path width of 0.32mm.

[0071] Figure 7 The pictures of the cutting paths before and after deburring in this embodiment are as follows. As can be seen from Figure (a), before cleaning with the cleaning solution, many burrs were generated on the cutting paths of the QFN frame, while after cleaning with the cleaning solution, the burrs were basically removed.

[0072] Example 2

[0073] For the QFN5×5×0.75-32L frame, the specific implementation steps are as follows:

[0074] Step 1: For the QFN frame after plastic encapsulation and post-curing by the traditional QFN packaging process, first use a manual film laminating machine to fix the frame on the ring, and then use a transparent acid-resistant UV film with a thickness of 125μm to stick it on the back of the plastic-encapsulated QFN frame.

[0075] Step 2: Perform a cut with a cutting width of 0.42 mm, a cutting depth of 0.10 mm, a cooling water flow rate of 3 L / min, a spray water flow rate of 2 L / min, a spindle speed of 28,000 r / min, and a feed speed of 30 mm / s.

[0076] Step 3: Place the cut QFN frame in a copper burr cleaning solution for etching for 3.5 minutes. The cleaning solution ratio is 3.5% sulfuric acid, 10.0% hydrogen peroxide, 2% stabilizer butanediol, 0.5% brightener butanol phosphate, 0.5% corrosion inhibitor (a mixture of dicyandiamide formaldehyde resin and modified polyacrylamide in a mass ratio of 1:1), and 83.5% deionized water. After etching, take out the QFN frame for pure water cleaning and oven drying.

[0077] Step 4: Then, the QFN frame and the acid-resistant UV film are irradiated with UV light for 1 minute to remove the adhesion of the acid-resistant UV film to the QFN frame. Then, an adhesive film is attached to the surface of the entire acid-resistant UV film, and the adhesive film is removed to separate the acid-resistant UV film from the QFN frame.

[0078] Step 5: The QFN frame that has been deburred is subjected to traditional electroplating and marking treatment. Finally, secondary cutting and separation is performed under the conditions of cooling water flow rate 2L / min, spray water flow rate 2L / min, spindle speed 23000r / min, feed speed 30mm / s, and cutting path width of 0.30mm.

[0079] Example 3

[0080] For the QFN6×6×0.75-48L frame, the specific implementation steps are as follows:

[0081] Step 1: For the QFN frame after plastic encapsulation and post-curing by the traditional QFN packaging process, first use a manual film laminating machine to fix the QFN frame on the ring, and then use a transparent acid-resistant UV film with a thickness of 150μm to manually stick it on the back of the plastic-encapsulated QFN frame.

[0082] Step 2: Perform a cut with a cutting width of 0.40 mm, a cutting depth of 0.10 mm, a cooling water flow rate of 3 L / min, a spray water flow rate of 2 L / min, a spindle speed of 28000 r / min, and a feed speed of 30 mm / s.

[0083] Step 3: Place the cut QFN frame in a copper burr cleaning solution for 3.5 minutes. The cleaning solution ratio is 3.0% sulfuric acid, 9% hydrogen peroxide, 1.5% stabilizer, 0.5% brightener, 0.5% corrosion inhibitor, and 85.5% deionized water. After the etching is completed, take out the QFN frame for pure water cleaning and oven drying.

[0084] Step 4: Then, the QFN frame and the acid-resistant UV film are irradiated with UV light for 1 minute to remove the adhesion of the acid-resistant UV film to the QFN frame. Then, an adhesive film is attached to the surface of the entire acid-resistant UV film, and the adhesive film is removed to separate the acid-resistant UV film from the QFN frame.

[0085] Step 5: The QFN frame that has been deburred is subjected to traditional electroplating and marking treatment. Finally, secondary cutting and separation is performed under the conditions of cooling water flow rate 2L / min, spray water flow rate 2L / min, spindle speed 23000r / min, feed speed 30mm / s, and cutting path width of 0.30mm.

[0086] Example 4

[0087] For the QFN4×4×0.75-20L frame, the specific implementation steps are as follows:

[0088] Step 1: For the QFN frame after plastic encapsulation and post-curing by the traditional QFN packaging process, first use a manual film laminating machine to fix the QFN frame on the ring, and then use a transparent acid-resistant UV film with a thickness of 125μm to manually stick it on the back of the plastic-encapsulated QFN frame.

[0089] Step 2: Perform a cut with a cutting width of 0.42 mm, a cutting depth of 0.10 mm, a cooling water flow rate of 3 L / min, a spray water flow rate of 2 L / min, a spindle speed of 28,000 r / min, and a feed speed of 30 mm / s.

[0090] Step 3: Place the cut QFN frame in a copper burr cleaning solution for 3 minutes. The cleaning solution ratio is 3.5% sulfuric acid, 10.0% hydrogen peroxide, 2% stabilizer, 0.5% brightener, 0.5% corrosion inhibitor, and 83.5% deionized water. After the etching is completed, take out the QFN frame for pure water cleaning and oven drying.

[0091] Step 4: Then, the QFN frame and the acid-resistant UV film are irradiated with UV light for 1 minute to remove the adhesion of the acid-resistant UV film to the QFN frame. Then, an adhesive film is attached to the surface of the entire acid-resistant UV film, and the adhesive film is removed to separate the acid-resistant UV film from the QFN frame.

[0092] Step 5: The QFN frame that has been deburred is subjected to traditional electroplating and marking treatment. Finally, secondary cutting and separation is performed under the conditions of cooling water flow rate 2L / min, spray water flow rate 2L / min, spindle speed 23000r / min, feed speed 30mm / s, and cutting path width of 0.30mm.

[0093] Comparative Example 1

[0094] For the QFN3×3×0.75-16L frame, the specific implementation steps are as follows:

[0095] Step 1: For the frame that has been molded and post-cured by the traditional QFN packaging process, first use a manual film laminating machine to fix the frame on the ring film, and then use blue UV film to manually stick it on the back of the molded QFN frame.

[0096] The blue UV film used has the following specific specifications:

[0097] The total thickness is 125 μm, the layer thickness used is 90 μm (including 80 μm blue PVC substrate, 10 μm modified acrylic adhesive), and the transparent PET release film is 35 μm.

[0098] Better adhesion before UV irradiation:

[0099] Adhesion to steel plate - before light exposure (180° peeling, 20min), adhesion ≥ 650gf / 25mm,

[0100] Adhesion to steel plate - after exposure to light (180° peeling, leaving for 20 minutes), adhesion ≤ 25gf / 25mm.

[0101] Step 2: During a cut, due to the use of blue UV film, the cutting path cannot be clearly seen on the display screen of the cutting machine, and therefore the tool cannot be accurately aligned.

[0102] Step 3: Subsequent experiments cannot be performed.

[0103] Comparative Example 2

[0104] For the QFN3×3×0.75-16L frame, the specific implementation steps are as follows:

[0105] Step 1: For the frame that has been molded and post-cured by the traditional QFN packaging process, first use a manual film laminating machine to fix the frame on the ring film, and then use a translucent UV film to manually stick it on the back of the molded QFN frame.

[0106] The translucent UV film used has the following specific specifications:

[0107] The total thickness is 205 μm, the layer thickness used is 170 μm (including 150 μm PO substrate, 20 μm modified acrylic adhesive), and the transparent PET release film is 35 μm.

[0108] Better adhesion before UV irradiation:

[0109] Adhesion to steel plate - before light exposure (180° peeling, 20min), adhesion ≥ 650gf / 25mm,

[0110] Adhesion to steel plate - after exposure to light (180° peeling, leaving for 20 minutes), adhesion ≤ 25gf / 25mm.

[0111] Step 2: During a cut, due to the use of a thick translucent UV film, the cutting path cannot be clearly seen on the display screen of the cutting machine, and the tool cannot be accurately aligned.

[0112] Step 3: Subsequent experiments cannot be performed.

[0113] It can be seen from Comparative Examples 1 and 2 that neither the blue UV film nor the translucent UV film is applicable to the method of the present invention. The present invention requires the use of a transparent acid-resistant UV film to achieve a one-time cutting and subsequent burr removal process.

[0114] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for removing wettable flank QFN burrs, characterized in that: The following steps are involved: S1, plastic-encapsulating the chip according to the QFN packaging process, and after the plastic-encapsulation is completed, pasting a transparent acid-resistant UV film on the back of the plastic-encapsulated QFN frame; S2, cutting the QFN frame with the acid-resistant UV film; S3, placing the cut QFN frame in a copper burr cleaning solution for chemical etching; S4, after the chemical etching is completed, the QFN frame is taken out for cleaning and drying, and then the QFN frame and the acid-resistant UV film are subjected to UV light irradiation treatment; S5, after the UV light irradiation treatment, a sticky film is attached to the surface of the acid-resistant UV film, and the sticky film is removed to separate the acid-resistant UV film from the QFN frame; S6, electroplating, marking, and secondary cutting processes are performed.

2. The method for removing wettable flank QFN burrs according to claim 1, characterized in that: In S1, the acid-resistant UV film includes a substrate layer, an adhesive layer and a release layer, the substrate layer is a PO film or a PET film, the adhesive layer is an acrylic layer, and the release layer is a PET film.

3. The method for removing wettable flank QFN burrs according to claim 1, characterized in that: In S1, the acid-resistant UV film has a thickness of 100-150 μm.

4. The method for removing wettable flank QFN burrs according to claim 1, characterized in that: In S1, the adhesion of the acid-resistant UV film to the steel plate is: before illumination, the adhesion is ≥650 gf / 25 mm; after illumination, the adhesion is ≤25 gf / 25 mm.

5. The method for removing wettable flank QFN burrs according to claim 1, characterized in that: In S3, the composition of the copper burr cleaning solution is, by mass percentage, 3%-4% sulfuric acid, 9%-11% hydrogen peroxide, 1.5%-2.5% stabilizer, 0.4%-0.6% brightener, 0.4%-0.6% corrosion inhibitor, and 81.5%-85.5% deionized water.

6. The method for removing wettable flank QFN burrs according to claim 5, characterized in that: The stabilizer is butanediol, the brightener is butanol phosphate, and the corrosion inhibitor is a mixture of dicyandiamide formaldehyde resin and modified polyacrylamide.

7. The method for removing wettable flank QFN burrs according to claim 1, characterized in that: In S3, chemical etching is performed at room temperature.

8. The method for removing wettable flank QFN burrs according to claim 1, characterized in that: In S3, the chemical etching time is 2-4 minutes.

9. The method for removing wettable flank QFN burrs according to claim 1, characterized in that: In S4, the UV light irradiation treatment time is 1-2 minutes.

10. The method for removing wettable flank QFN burrs according to claim 1, characterized in that: In S5, the adhesive film is a tear-off tape.

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