Method for preventing chip from inclining after reflow soldering of single-row pin side key fingerprint module

Abstract

The invention discloses a method for preventing a chip from inclining after reflow soldering of a single-row pin side key fingerprint module, and the method comprises the following steps: S1, selecting a bonding pad region on a flexible printed circuit (FPC) for a bonding pad of the single-row pin side key fingerprint module, and selecting blank left and right regions as supporting point adding positions; s2, white ink blocks with the design size of 0.8 * 0.45 mm are designed and used as supporting points of the fingerprint chip, and it is ensured that the thickness of each white ink block is 5-15 microns higher than the surface of the FPC; s3, manufacturing a white ink block, wherein the screen printing technology is adopted, and the white ink block is printed in a designated area of a flexible printed circuit (FPC); and S4, adding a white ink block process to integrate the printing process of the white ink block into the manufacturing process of the FPC. The blank areas on the left and right sides of the bonding pad area are selected as the supporting point adding positions, and the white ink blocks are designed and manufactured as the supporting points of the fingerprint chip, so that the problem that the chip is easy to incline in the reflow soldering process of the single-row pin side key fingerprint module is successfully solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fingerprint module production, and specifically provides a method for preventing the chip of a single-row pin side-key fingerprint module from tilting after reflow soldering. Background Art

[0002] In recent years, as a representative of portable intelligent products, the performance of smart phones has been increasing day by day. At the same time, while pursuing higher performance, the design of smart phones has become increasingly lightweight and compact. This trend has directly promoted the development of various components, including side-key fingerprint modules, towards smaller sizes and lighter weights. The side-key fingerprint module, as a key component in smart phones to achieve fingerprint unlocking and recognition functions, its miniaturization has become an inevitable choice for the industry development.

[0003] Traditionally, due to the relatively large size of the side-key fingerprint module, designers could reserve sufficient space on its FPC flexible circuit board and fingerprint chip to design symmetric support pads. These support pads play a crucial role in the reflow soldering process. They can effectively prevent the fingerprint chip from tilting excessively due to the thermal stress during the soldering process, thus ensuring the stability and reliability of the module in subsequent assembly.

[0004] However, with the continuous progress of smart phone technology and consumers' continuous pursuit of thinner and lighter products, the side-key fingerprint module faces unprecedented miniaturization challenges. When the module volume is reduced to a certain extent, the space originally used for the support pad design is greatly compressed or even completely disappears. In this case, designers have to abandon the traditional symmetric support pad design and instead adopt a single-row pin layout to meet the requirements of module miniaturization.

[0005] However, the side-key fingerprint module with a single-row pin design faces a new problem during the reflow soldering process: due to the lack of an effective support structure, the fingerprint chip is prone to excessive tilting during the soldering process. This tilting not only affects the appearance and structural stability of the module, but more importantly, when the tilting degree exceeds a certain threshold, such as 0.07 mm, it will directly affect the assembly effect and performance of the module on the mobile phone, and even lead to abnormal use.

[0006] Therefore, how to effectively prevent the excessive tilting of the fingerprint chip after reflow soldering while ensuring the miniaturization of the side-key fingerprint module has become an urgent technical problem to be solved in the current smart phone manufacturing field. Summary of the Invention

[0007] The purpose of the present invention is to solve the above technical problems, and thus provides a method for preventing the chip of a single-row pin side-key fingerprint module from tilting after reflow soldering; To solve the above technical problems, the present invention provides the following technical solutions: The present invention provides a method for preventing the chip from tilting after reflow soldering of a single-row side-button fingerprint module, including the following steps: S1 Select the pad area. On the flexible printed circuit board (FPC), for the pads of the single-row side-button fingerprint module, select the blank areas on the left and right sides as the positions for adding support points; S2 Design white ink blocks: Design several white ink blocks with a size of 0.8 * 0.45 mm to be used as support points for the fingerprint chip, ensuring that the thickness of each white ink block is 5 - 15 μm higher than the surface of the FPC to provide sufficient support force and avoid affecting the soldering quality; S3 Fabricate white ink blocks: Use screen printing technology to print white ink blocks in the specified area of the flexible printed circuit board (FPC) according to the designed size and position.

[0008] S4 Add the white ink block process: Incorporate the printing process of the white ink block into the manufacturing process of the FPC, specifically arranging it before reflow soldering.

[0009] Optionally, in step S1, when selecting the blank areas on the left and right sides of the pad area as the positions for adding support points, it further includes calculating and determining the optimal positions and quantities of the support points according to the size and weight of the fingerprint module, as well as the coefficient of thermal expansion during the reflow soldering process, to ensure sufficient support force is provided without affecting the overall layout of the circuit board.

[0010] Optionally, in step S2, when designing the white ink blocks, it further includes selecting an ink material with high heat resistance and high adhesion to ensure that the white ink blocks will not deform or fall off due to high temperature during the reflow soldering process, thus maintaining a stable support function.

[0011] Optionally, in step S3, when fabricating the white ink blocks using screen printing technology, it further includes using precise screen printing equipment and calibration tools to ensure that the size, position, and thickness of the white ink blocks meet the design requirements and the printing quality is uniform.

[0012] Optionally, in step S4, when incorporating the printing process of the white ink block into the manufacturing process of the FPC, it further includes performing drying and curing treatments after printing the white ink blocks to ensure that the ink blocks are completely cured and reach the required hardness and stability.

[0013] Optionally, when designing the white ink blocks in step S2, further consider the bonding force between the ink blocks and the surface of the FPC. By optimizing the ink formula or adding surface treatment processes, such as plasma treatment or coating adhesives, to enhance the adhesion strength between the ink blocks and the FPC, ensuring that the white ink blocks will not fall off or shift during reflow soldering and subsequent use, and continuously providing a stable support effect.

[0014] Optionally, after manufacturing the white ink block in step S3, an additional visual inspection process is added. Professional personnel or an automated vision inspection system is used to inspect the printing quality of each white ink block one by one, ensuring that the edges of the ink block are clear, free of defects and overflows, and tightly bonded to the FPC surface without gaps, so as to ensure that the ink block can play the best supporting role during the reflow soldering process, while reducing production waste and quality problems caused by poor printing.

[0015] In summary, the present invention has the following beneficial effects: In this application, by selecting the blank areas on both the left and right sides of the pad area as the additional position for the support points and designing and manufacturing the white ink block as the support point for the fingerprint chip, the problem that the chip is prone to tilt during the reflow soldering process of the single-row pin side-button fingerprint module is successfully solved. The white ink block provides sufficient support force to ensure that the chip remains stable during the soldering process and will not tilt excessively due to thermal stress, which greatly improves the stability of the module and lays a solid foundation for subsequent assembly and performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of the white ink block on the FPC of the present invention; Figure 2 It is a schematic structural diagram when the tilt value reaches the critical value of 0.07 mm when the thickness of the white oil block of the present invention is 5 um; Figure 3 It is a physical diagram of adding the white oil block of the present invention; Figure 4 It is a physical cross-sectional diagram of the side of the white oil block of the present invention; Figure 5 It is an effect diagram of the support of the fingerprint chip after adding the white oil block of the present invention; Figure 6 It is a schematic structural diagram of the support pad designed on the existing FPC; Figure 7 It is a schematic structural diagram of the support pad designed for the existing fingerprint chip; Figure 8 It is a design diagram of the pad of the single-row pin fingerprint module; Figure 9 It is a physical diagram of the pad of the single-row pin fingerprint module; Figure 10 It is a schematic diagram of CAD tilt simulation; Figure 11 It is a physical cross-sectional diagram of the chip tilt. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] Embodiment: The present invention provides a method for preventing the chip from tilting after reflow soldering of a single-row side-key fingerprint module, including the following steps: S1 Select the pad area. On the flexible printed circuit board (FPC), for the pads of the single-row side-key fingerprint module, select the blank left and right areas on both sides as the positions for adding support points. S2 Design white ink blocks: Design several white ink blocks with a size of 0.8 * 0.45 mm to be used as the support points for the fingerprint chip, ensuring that the thickness of each white ink block is 5 - 15 um higher than the surface of the FPC to provide sufficient support force and avoid affecting the soldering quality. S3 Manufacture white ink blocks: Use screen printing technology to print white ink blocks in the specified area of the flexible printed circuit board (FPC) according to the designed size and position.

[0019] S4 Add the process of white ink blocks: Incorporate the printing process of white ink blocks into the manufacturing process of the FPC, and specifically arrange it before reflow soldering.

[0020] Printing white ink blocks before reflow soldering can ensure that only the predetermined areas are connected by solder during the soldering process, avoiding soldering defects such as bridging and short circuits. The printing of white ink blocks can also prevent the solder from flowing in the areas where soldering is not required, thereby reducing the waste of solder and reducing the copper pollution of the soldering bath. Incorporating the printing process of white ink blocks into the manufacturing process of the FPC and arranging it before reflow soldering is to protect the copper coating and circuits on the board surface, improve the soldering quality and reliability, and improve the appearance and performance of the product.

[0021] In step S1, when selecting the blank areas on the left and right sides of the pad area as the positions for adding support points, it further includes calculating and determining the optimal positions and quantities of the support points according to the size and weight of the fingerprint module, as well as the coefficient of thermal expansion during the reflow soldering process, to ensure sufficient support force without affecting the overall layout of the circuit board.

[0022] In step S2, when designing white ink blocks, it further includes selecting an ink material with high heat resistance and high adhesion to ensure that the white ink blocks will not deform or fall off due to high temperature during the reflow soldering process, thus maintaining a stable support function.

[0023] In step S3, when manufacturing the white ink block using screen printing technology, it further includes using precise screen printing equipment and calibration tools to ensure that the size, position, and thickness of the white ink block meet the design requirements and the printing quality is uniform.

[0024] In this application, by selecting the blank areas on the left and right sides of the pad area as the additional positions for the support points and designing the white ink block with specific dimensions and thickness, first, analyze the pad area of the single-row pin side-button fingerprint module to determine its structural and layout characteristics. Since the module is small in size and uses a single-row pin design, the traditional symmetric support pads are no longer applicable. Look for suitable blank areas on the left and right sides of the pad area as the additional positions for the support points. These areas need to be flat enough and do not affect the normal function of the circuit board.

[0025] According to the size, weight of the module, and the coefficient of thermal expansion during the reflow soldering process, through calculation and analysis, determine the optimal positions and quantities of the support points to ensure that these support points can provide sufficient support force without interfering with the overall layout of the circuit board.

[0026] Specifically: Measure and record the length, width, height, and weight of the module, and find the coefficients of thermal expansion of the main materials in the module, such as the circuit board substrate, solder, chips, etc. These coefficients can usually be found in the data manuals of the materials or relevant literature.

[0027] According to the process requirements of reflow soldering, estimate the temperature change range that the module may experience during the soldering process, and use the thermal expansion formula to calculate the thermal expansion amounts of the various materials in the module within the temperature change range. For one-dimensional cases, the linear expansion coefficient formula: ΔL = L × α × ΔT, where ΔL is the length change amount, L is the initial length, α is the linear expansion coefficient, and ΔT is the temperature change amount. For three-dimensional cases, use the volume expansion coefficient formula for similar calculations.

[0028] According to the structural and layout characteristics of the module and the calculation results of the thermal expansion amounts, preliminarily determine the positions of the support points. These positions should be located in the areas of the module that are easily affected by thermal expansion and require additional support.

[0029] Consider the weight of the module and the stress that may be generated by thermal expansion, and evaluate the support force required for each support point.

[0030] Ensure that the positions of the selected support points do not interfere with the overall layout of the circuit board, such as not affecting the signal transmission path and not blocking key components, etc.

[0031] Model and analyze the module using finite element analysis (FEA) or other simulation software. By simulating the thermal expansion and stress distribution during the soldering process, further optimize the position and number of support points. The simulation analysis can help identify potential stress concentration areas and guide the rational layout of support points.

[0032] Fabricate a module prototype according to the optimized design scheme and conduct reflow soldering tests. Observe and record indicators such as the deformation of the module and the chip tilt value.

[0033] If the test results do not meet the requirements, further adjust the position and number of support points according to the actual situation. The process of simulation analysis, prototype fabrication, and testing needs to be repeated until satisfactory results are achieved.

[0034] Through the above calculation and analysis methods, it can be ensured that the selected support points can provide sufficient support force to resist thermal expansion and stress without interfering with the overall layout of the circuit board.

[0035] Design and Fabrication of White Ink Blocks Dimension Design: According to the position of the support points and the characteristics of the module, design the size of the white ink block to be 0.8 * 0.45 mm. This size will neither be too large to affect the surrounding circuits nor ensure sufficient support area.

[0036] Thickness Control: The thickness of the white ink block is precisely controlled between 5 - 15 μm. This thickness range is obtained based on the solder thickness of 15 - 25 μm during reflow soldering and the comprehensive consideration of the support effect of the white ink block on the fingerprint chip. An overly thick white ink block will interfere with the soldering process, while an overly thin one cannot provide sufficient support force.

[0037] Material Selection: Select an ink material with high heat resistance and high adhesion to fabricate the white ink block. This material can maintain its shape and position unchanged in the high-temperature environment of reflow soldering and ensure a tight bond with the circuit board.

[0038] Fabrication Process: Adopt precise stencil printing technology and calibration tools to print the white ink block in the specified area of the circuit board according to the designed size and position. During this process, parameters such as printing pressure, speed, and ink viscosity need to be strictly controlled to ensure that the size, position, and thickness of the white ink block meet the design requirements.

[0039] The precisely designed white ink block provides stable and effective support for the fingerprint chip. During the reflow soldering process, the white ink block can resist thermal stress and mechanical stress, preventing the chip from tilting excessively.

[0040] Experiments have shown that when the thickness of the white ink block is controlled between 5 - 15um, the tilt value of the fingerprint chip can be maintained within a safe range of 0.07mm, and this result is far lower than the critical value that affects the assembly effect and performance of the module.

[0041] Improved soldering quality: The presence of the white ink block does not interfere with the soldering process. Instead, it can ensure the quality and reliability of the solder joints. At the same time, due to the tight bonding between the white ink block and the circuit board, it can also enhance the mechanical strength of the solder joints to a certain extent.

[0042] In summary, by precisely selecting the position of the support points and designing the white ink block with specific dimensions and thickness, this method has successfully solved the problem of chip tilt during the reflow soldering process of the single - row - pin side - key fingerprint module.

[0043] In step S4, when integrating the printing process of the white ink block into the production process of the FPC, it further includes drying and curing treatments after printing the white ink block to ensure that the ink block is completely cured and reaches the required hardness and stability.

[0044] Through the drying and curing treatments, solvents or other volatile components in the white ink block will be removed, making the white ink block harder and more stable. The improvement in hardness and stability helps the white ink block withstand high temperatures and mechanical stresses during the reflow soldering process and maintain its shape and position unchanged.

[0045] The main role of the white ink block in reflow soldering is to provide support and prevent the fingerprint chip from tilting due to solder flow or thermal expansion. The drying and curing treatments can ensure that the white ink block has sufficient hardness and stability to provide effective support.

[0046] During the reflow soldering process, the thickness of the solder may change due to various factors. After the drying and curing treatments, the white ink block, with its improved hardness and stability, can better adapt to the changes in solder thickness and continuously provide stable support for the fingerprint chip.

[0047] For some types of white ink blocks, natural drying at room temperature can be used. This method is simple and easy to implement, but it takes a long time and is greatly affected by environmental humidity and temperature. By using heating equipment such as ovens and hot air guns to heat - dry the white ink block, this method can speed up the drying rate and improve the drying effect.

[0048] UV curing: For some white ink blocks containing photosensitive components, the UV curing method can be used for treatment. UV curing has the advantages of fast speed and high efficiency and can make the white ink block reach the required hardness and stability in a short time.

[0049] The white ink block after drying and curing treatment can maintain a stable supporting effect during reflow soldering and subsequent use, prevent the fingerprint chip from tilting, contribute to improving the quality and reliability of the module, and reduce the risks of assembly problems and performance degradation caused by chip tilting.

[0050] The stable supporting effect of the white ink block also helps to enhance the overall stability of the module. When the module is subjected to external impacts or vibrations, the white ink block can absorb part of the energy, reduce the impact on the fingerprint chip, and thus protect the module from damage.

[0051] Through drying and curing treatment, the performance of the white ink block has been significantly improved, which helps to optimize the production process and reduce production delays and scrap rates caused by unstable performance of the white ink block.

[0052] When designing the white ink block in step S2, further consider the bonding force between the ink block and the FPC surface. By optimizing the ink formula or adding surface treatment processes, such as using plasma treatment or coating adhesives, to enhance the adhesion strength between the ink block and the FPC, ensuring that the white ink block will not fall off or shift during reflow soldering and subsequent use, and continuously providing a stable supporting effect.

[0053] The firmness of the ink is closely related to the quality of the ink raw materials. Selecting high-quality pigments, resins, and additives can improve the anti-ultraviolet, abrasion-resistant, and chemical corrosion-resistant properties of the ink, thereby enhancing the adhesion strength of the ink.

[0054] According to factors such as the material of the FPC, printing method, and use environment, reasonably adjust the ink formula. For example, increasing the resin content or changing the type of resin can improve the wetting performance of the ink on the FPC surface, and thus enhance the adhesion strength.

[0055] Adding an appropriate amount of tackifier or curing agent to the ink formula can improve the adhesion between the ink and the FPC. The tackifier can increase the viscosity of the ink, making it better adhere to the FPC surface; the curing agent can make the ink cure quickly after printing, forming a firm bonding layer.

[0056] Before printing, thoroughly clean the FPC surface to remove pollutants such as dust, grease, and moisture, which will hinder the combination between the ink and the FPC and reduce the adhesion strength.

[0057] Adopt methods such as plasma treatment, flame treatment, or chemical treatment to activate the FPC surface. These treatment methods can change the physical structure and chemical properties of the FPC surface, increase its surface energy and roughness, and thus enhance the adhesion strength between the ink and the FPC.

[0058] Apply a primer layer with good compatibility with the ink on the surface of the FPC. The primer layer can fill the minute defects on the FPC surface, improve the surface flatness, and provide a good adhesion foundation for the ink, which helps to enhance the adhesion between the ink and the FPC.

[0059] By optimizing the ink formula or adding surface treatment processes, the adhesion strength between the white ink block and the FPC is significantly enhanced. This enables the white ink block to maintain a stable supporting effect during reflow soldering and subsequent use, and it is not easily detached or displaced.

[0060] The enhanced adhesion strength helps to improve the quality and reliability of the entire module. Even in the face of harsh usage environments such as high temperature, high humidity, or mechanical stress, the white ink block can maintain its integrity and continuously provide stable support for the fingerprint chip.

[0061] Due to the enhanced adhesion strength between the white ink block and the FPC, the production problems and quality risks caused by the detachment or displacement of the white ink block are significantly reduced. This helps to improve production efficiency, reduce the defective rate, and enhance customer satisfaction.

[0062] After manufacturing the white ink block in step S3, add a visual inspection process. Have professionals or use an automated vision inspection system to check the printing quality of each white ink block one by one, ensuring that the edges of the ink block are clear, defect-free, non-overflowing, and tightly bonded to the FPC surface without gaps, so as to ensure that the ink block can play the best supporting role during reflow soldering and reduce production waste and quality problems caused by poor printing.

[0063] Visual inspection can directly observe the printing effect of the white ink block, including edge clarity, defect conditions, overflow conditions, etc. Through one-by-one inspection, white ink blocks with poor printing can be promptly detected and removed to ensure that each white ink block meets the quality requirements.

[0064] Visual inspection checks whether the edges of the white ink block are clear and neat, without blur or serrated phenomena. Edge clarity is one of the important indicators to measure printing quality. Check whether there are defects such as bubbles, pinholes, cracks, etc. on the surface of the white ink block. These defects affect the performance and service life of the white ink block, so they must be strictly controlled. Check whether there is overflow or diffusion of the white ink block to ensure that its combination with the FPC surface is tight without gaps. Overflow or diffusion may lead to a decrease in the bonding force between the white ink block and the FPC, affecting the stability of the module.

[0065] As mentioned in the background art of the present application, in the reflow soldering process, the single-row side-button fingerprint module is prone to chip tilt due to the lack of effective support. This is mainly because the traditional support method is no longer applicable in the miniaturized and thin-and-light module design. Through a detailed analysis of the module pad area, the present application precisely selects the blank areas on the left and right sides of the pad area as the positions for adding support points. These positions will neither affect the normal layout and function of the circuit board nor provide necessary support for the chip.

[0066] The present application designs a white ink block with a size of 0.8*0.45 mm and a thickness of 5-15 μm. This size and thickness range are obtained based on a comprehensive consideration of the module size, weight, and coefficient of thermal expansion during the reflow soldering process. By precisely controlling the thickness of the white ink block, it can ensure that while providing sufficient support force, it will not interfere with the soldering process or affect the soldering quality.

[0067] Through means such as CAD simulation, the present application verifies the support effect of the white ink block on the fingerprint chip. When the thickness of the white ink block is 5-15 μm, it can effectively support the fingerprint chip and keep its tilt value within a safe range of 0.07 mm. In addition, the present application also considers the thermal expansion factor during the reflow soldering process of the module, and further improves the stability and reliability of the support structure by optimizing the position and quantity of the support points.

[0068] In practical applications, the support structure design scheme proposed by the present application has been verified. By precisely selecting the position of the support points and designing the appropriate size and thickness of the white ink block, the problem of chip tilt occurring due to the lack of effective support during the reflow soldering process of the single-row side-button fingerprint module has been successfully solved. This not only improves the soldering quality of the module and the stability of subsequent assembly but also provides strong technical support for the development of portable intelligent products such as smart phones.

[0069] The present application selects the blank areas on the left and right sides of the pad area as the positions for adding support points and designs and manufactures a white ink block as the support point for the fingerprint chip, successfully solving the problem that the chip of the single-row side-button fingerprint module is prone to tilt during the reflow soldering process. The white ink block provides sufficient support force to ensure that the chip remains stable during the soldering process and will not tilt excessively due to thermal stress. This greatly improves the stability of the module and lays a solid foundation for subsequent assembly and performance.

[0070] When selecting the position of the support points, the present application further considers the size, weight of the fingerprint module, and the coefficient of thermal expansion during the reflow soldering process. By calculating, the optimal position and quantity of the support points are determined to ensure that the support points can provide just the right support force, neither causing chip tilt due to insufficient support nor affecting the overall layout of the circuit board due to excessive support.

[0071] This application selects an ink material with high heat resistance and high adhesion to make the white ink block. This ink material can maintain a stable form during the reflow soldering process and will not deform or fall off due to high temperature, thus continuously providing a stable supporting effect, which enhances the durability of the ink block and extends the service life of the module.

[0072] By adopting the stencil printing technology and combining precise printing equipment and calibration tools, this application ensures that the size, position, and thickness of the white ink block meet the design requirements, and the printing quality is uniform.

[0073] After printing the white ink block, this application conducts drying and curing treatments to ensure that the ink block is completely cured and reaches the required hardness and stability. This step enhances the mechanical strength and wear resistance of the ink block, enabling it to continuously provide a stable supporting effect during the reflow soldering and subsequent use processes.

[0074] By optimizing the ink formula or adding surface treatment processes, this application enhances the bonding force between the white ink block and the FPC surface, which ensures that the ink block will not fall off or shift during the reflow soldering and subsequent use processes, continuously providing stable support for the fingerprint chip. This enhanced bonding force greatly improves the reliability and durability of the module.

[0075] The method of this application is applicable to miniaturized single-row pin side-button fingerprint modules, solving the problem that the traditional support pad design cannot meet the miniaturization requirements. Through a unique support point design, this application successfully realizes the effective support for the fingerprint chip within a limited space, meeting the requirements of portable intelligent products such as smartphones for miniaturized and lightweight components, which enhances the competitiveness of the products and provides strong support for the thin and light design of terminal products such as smartphones.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preventing the chip from tilting after reflow soldering of a single-row side key fingerprint module, characterized in that: The following steps are involved: S1 selects the pad area, and on the flexible circuit board FPC, for the pad of the single-row side key fingerprint module, selects the blank left and right areas as the support point addition positions; S2 Design white ink blocks: Design several white ink blocks with a size of 0.8 * 0.45mm to serve as support points for the fingerprint chip. Ensure that the thickness of each white ink block is 5-15um higher than the FPC surface to provide sufficient support and avoid affecting the welding quality. S3 makes white ink blocks: using screen printing technology, print white ink blocks in the designated area of ​​the flexible circuit board FPC according to the designed size and position. S4 adds a white ink block process: the white ink block printing process is integrated into the FPC production process, and is specifically arranged to be carried out before reflow soldering.

2. A method for preventing chip tilting after reflow soldering of a single-row pin side key fingerprint module according to claim 1, characterized in that: In step S1, when the blank areas on the left and right sides of the pad area are selected as the locations for adding support points, it further includes calculating and determining the optimal positions and number of support points based on the size and weight of the fingerprint module and the thermal expansion coefficient during the reflow soldering process to ensure that sufficient supporting force is provided without affecting the overall layout of the circuit board.

3. A method for preventing chip tilting after reflow soldering of a single-row side key fingerprint module according to claim 1, characterized in that: In step S2, when designing the white ink block, it further includes selecting an ink material with high heat resistance and high adhesion to ensure that the white ink block will not be deformed or fall off due to high temperature during the reflow soldering process, thereby maintaining a stable supporting effect.

4. A method for preventing chip tilting after reflow soldering of a single-row pin side key fingerprint module according to claim 1, characterized in that: In step S3, when the white ink block is made by screen printing technology, it further includes using precise screen printing equipment and calibration tools to ensure that the size, position and thickness of the white ink block meet the design requirements and the printing quality is uniform.

5. The method for preventing the chip from tilting after reflow soldering of a single-row pin side key fingerprint module according to claim 1, characterized in that: In step S4, when the printing process of the white ink block is integrated into the production process of the FPC, it further includes drying and curing treatment after printing the white ink block to ensure that the ink block is completely cured and reaches the required hardness and stability.

6. A method for preventing chip tilting after reflow soldering of a single-row pin side key fingerprint module according to claim 3, characterized in that: When designing the white ink block in step S2, the bonding force between the ink block and the FPC surface is further considered. The ink formula is optimized or a surface treatment process is added, such as plasma treatment or adhesive coating, to enhance the adhesion strength between the ink block and the FPC. This ensures that the white ink block will not fall off or shift during reflow soldering and subsequent use, and continues to provide a stable support effect.

7. A method for preventing chip tilting after reflow soldering of a single-row pin side key fingerprint module according to claim 4, characterized in that: After the white ink block is made in step S3, a visual inspection process is added, and the printing quality of the white ink block is checked one by one by a professional or using an automated visual inspection system to confirm that the ink block has a clear edge, no defects, no overflow, and is tightly combined with the FPC surface without gaps, so as to ensure that the ink block can play the best supporting role during the reflow soldering process, while reducing production waste and quality problems caused by poor printing.

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